The arrays are list-like objects whose prototype has methods to perform traversal and mutation operations. Neither the length of a array nor the types of its elements are fixed. The arrays are used to store multiple values in a single variable.

1 Creating an Array

create an ARRAY
Operador Xsql <array name='name'>
Syntax var mArrName = [value1, value2, ...];
Return An array.
Copy 
<xsql-script>
    <body>
        <array name='cities'>
            <string>Barcelona</string>
            <string>Paris</string>
            <string>Roma</string>
        </array>

        <println>Cities array : <cities/></println>
    </body>
</xsql-script>
Cities array : [Barcelona,Paris,Roma]
Copy 
var mArrayCities = ['Barcelona','Paris','Roma'];

console.log(`Cities array :  ${mArrayCities}`);
Cities array :  Barcelona,Paris,Roma

Spaces and line breaks are not important. A declaration can span multiple lines.

Copy 
var mArrayCountries = [
    'Portugal',
    'España',
    'Alemania'
];

console.log(`Countries array :  ${mArrayCountries}`);
Countries array :  Portugal,España,Alemania

2 Access an Array

Access to an array element is possible by referring to the index number.

access an ARRAY
Operador Xsql <array.get name='name'>
Syntax var mValue = Array[i];
Return Accesses the value.
Copy 
<xsql-script>
    <body>
        <array name='cities'>
            <string>Barcelona</string>
            <string>Paris</string>
            <string>Roma</string>
            <string>Budapest</string>
        </array>

        <set name='m_value1'>
            <array.get name='cities'>
                <number>0</number>
            </array.get>
        </set>

        <set name='m_value2'>
            <array.get name='cities'>
                <number>2</number>
            </array.get>
        </set>

        <println>First element : [<m_value1 />]</println>
        <println>Third element : [<m_value2 />]</println>
    </body>
</xsql-script>
First element : [Barcelona]
Third element : [Roma]
Copy 
var mArrayCities = ['Barcelona','Paris','Roma','Budapest'];

var mStrValue1 = mArrayCities[0];
var mStrValue2 = mArrayCities[2];

console.log(`First element : [${mStrValue1}]`);
console.log(`Third element : [${mStrValue2}]`);
First element : [Barcelona]
Third element : [Roma]

The first element of an array is at index 0, and the last element is at the index value equal to the value of the array's length property minus 1. For example, [0] is the first element, and [1] is the second element.

3 Changing element at an Array

change element at an ARRAY
Operador Xsql <array.set name='name'>
Syntax Array[i] = mValue;
Return Changed element.
Copy 
<xsql-script>
    <body>
        <array name='m_cities'>
            <string>Barcelona</string>
            <string>Paris</string>
            <string>Roma</string>
        </array>
   
        <println>Array cities before change: <m_cities /></println>

        <array.set>
     	    <m_cities/>
      	    <number>1</number>              
      	    <string>Budapest</string> 	 
        </array.set>   

        <println>Array cities after change: <m_cities /></println>
    </body>
</xsql-script>
Array cities before change: [Barcelona,Paris,Roma]
Array cities after change: [Barcelona,Budapest,Roma]
Copy 
var mArrayCities = ['Barcelona','Paris','Roma'];

console.log(`Array cities before change: :  ${mArrayCities}`);

mArrayCities[1] = 'Budapest';

console.log(`Array cities after change: :  ${mArrayCities}`);
Array cities before change: :  Barcelona,Paris,Roma
Array cities after change: :  Barcelona,Budapest,Roma

4 Loop over an Array

Using a for loop is the safest way to loop through an array.

Copy 
<xsql-script>
    <body>
        <array name='m_cities'>
            <string>Barcelona</string>
            <string>Paris</string>
            <string>Roma</string>
        </array>

        <set name='m_length'>
            <array.size name='m_cities' />
        </set>

        <set name='m_length'>
            <sub>
                <m_length/>
                1
            </sub>
        </set>
        
        <for name='i' start='0' end='${m_length}' step='1'>
            <do>
                <set name='m_city'>
                    <array.get name='m_cities'>
                        <number><i/></number>
                    </array.get>
                </set>
                <println>Array element [<i/>] : <m_city/></println>
            </do>
        </for>
    </body>
</xsql-script>
Array element [0] : Barcelona
Array element [1] : Paris
Array element [2] : Roma
Copy 
var mArrayCities = ['Barcelona','Paris','Roma'];
var mIntLength = mArrayCities.length;

for (i = 0; i < mIntLength; i++) {
  console.log(`Array element[${i}] : ${mArrayCities[i]}`)
}
Array element[0] : Barcelona
Array element[1] : Paris
Array element[2] : Roma
Copy 
var mArrayCities = ['Barcelona','Paris','Roma'];

mArrayCities.forEach(function(item, index, array) {
  console.log(`Array element[${index}] : ${item}`)
})
Array element[0] : Barcelona
Array element[1] : Paris
Array element[2] : Roma

5 Clear an array

Deletes all the elements of an array.

clear an ARRAY
Operador Xsql <array.clear name='array_name' />
Syntax mArrName = []
Return Clean array.
Copy 
<xsql-script>
    <body>
        <array name='m_cities'>
            <string>Barcelona</string>
            <string>Paris</string>
            <string>Roma</string>
        </array>

        <println>Array cities before of clears elements: <m_cities /></println>

        <array.clear name='m_cities' />

        <println>Array cities after of clears elements: <m_cities /></println>
    </body>
</xsql-script>
Array cities before of clears elements: [Barcelona,Paris,Roma]
Array cities after of clears elements: []
Copy 
var mArrayCities = ['Barcelona','Paris','Roma'];

console.log(`Array cities before of clears elements: ${mArrayCities}`);

mArrayCities = [];

console.log(`Array cities after of clears elements: ${mArrayCities}`);
Array cities before of clears elements: Barcelona,Paris,Roma
Array cities after remove element:

6 Properties

6.1 Array.length

The length property returns the number of elements in that array.

length PROPERTY
Operador Xsql <array.size name='name'>
Syntax mArrayName.length
Parameters

No parameters.
Return A Number, representing the number of elements in the array object
Copy 
<xsql-script>
    <body>
        <array name='m_cities'>
            <string>Barcelona</string>
            <string>Paris</string>
            <string>Roma</string>
        </array>

        <set name='m_result'>
            <array.size name='m_cities' />
        </set>

        <println>length cities array: <m_result /></println>
    </body>
</xsql-script>
length cities array: 3
Copy 
var mArrayCities = ['Barcelona','Paris','Roma'];

var mIntResult = mArrayCities.length;

console.log(`length cities array: ${mIntResult}`);
length cities array:: 3

Length

The value of the length property is an integer with a positive sign and a value less than 2 to the 32nd power (232).

7 Methods

7.1 Array.concat()

The concat() method is used to merge two or more arrays.

concat() METHOD
Syntax var mArrayNew = mArrayOld.concat([value1[, value2[, ...[, valueN]]]])
Parameters Arrays and/or values to concatenate into a new array.
Return A new Array.

The concat() method does not change the existing arrays, but instead returns a new array.

  • Concatenating two arrays

Copy 
<xsql-script>
    <body>
        <set name='m_cities1'>
            <array>
                <string>Barcelona</string>
                <string>Paris</string>
                <string>Roma</string>
            </array>
        </set>

          <set name='m_cities2'>
            <array>
                <string>Londres</string>
                <string>Lisboa</string>
                <string>Berlín</string>
            </array>
        </set>

         <set name='m_all_Cities'>
            <array.clone name='m_cities1' />
        </set>

        <iterator name='m_city2'>
            <in>
                <m_cities2/>
            </in>
            <do>
                <array.add name='m_all_Cities'>
                   <m_city2 />
                </array.add>    
            </do>
        </iterator>

        <println>Elements from array Cities1: <m_cities1 /></println>
        <println>Elements from array Cities2: <m_cities2 /></println>
        <println>Join of the two arrays: <m_all_Cities /></println>
    </body>
</xsql-script>
Elements from array Cities1: [Barcelona,Paris,Roma]
Elements from array Cities2: [Londres,Lisboa,Berlín]
Join of the two arrays: [Barcelona,Paris,Roma,Londres,Lisboa,Berlín]
Copy 
var mArrayCities = ['Barcelona','Paris','Roma'];
var mArrayCities2 = ['Londres','Lisboa', 'Berlin'];

var mArrAllCities = mArrayCities.concat(mArrayCities2);

console.log(`Cities array: ${mArrayCities}`);
console.log(`Cities2 array: ${mArrayCities2}`);
console.log(`Join two arrays: ${mArrAllCities}`);
Cities array: Barcelona,Paris,Roma
Cities2 array: Londres,Lisboa,Berlin
Join two arrays: Barcelona,Paris,Roma,Londres,Lisboa,Berlin

  • Concatenating three arrays

Copy 
<xsql-script>
    <body>
        <set name='m_cities1'>
            <array>
                <string>Barcelona</string>
                <string>Sevilla</string>
                <string>Valencia</string>
            </array>
        </set>

        <set name='m_cities2'>
            <array>
                <string>Roma</string>
                <string>Florencia</string>
                <string>Venecia</string>
            </array>
        </set>

        <set name='m_cities3'>
            <array>
                <string>Lisboa</string>
                <string>Oporto</string>
                <string>Aveiro</string>
            </array>
        </set>

        <println>Elements from array Cities1: <m_cities1 /></println>
        <println>Elements from array Cities2: <m_cities2 /></println>
        <println>Elements from array Cities3: <m_cities3 /></println>

         <set name='m_all_Cities'>
            <array.clone name='m_cities1' />
        </set>

        <for name='i' start='2' end='3' step='1'>
            <do>
                <iterator name='m_cities${i}'>
                    <in>
                        <get name='m_cities${i}'/>
                    </in>
                    <do>
                        <array.add name='m_all_Cities'>
                            <get name='m_cities${i}'/>
                        </array.add>    
                    </do>
                </iterator>
            </do>
        </for>
    
        <println>Join of the three arrays: <m_all_Cities /></println>
    </body>
</xsql-script>
Elements from array Cities1: [Barcelona,Sevilla,Valencia]
Elements from array Cities2: [Roma,Florencia,Venecia]
Elements from array Cities3: [Lisboa,Oporto,Aveiro]
Join of the three arrays: [Barcelona,Sevilla,Valencia,Roma,Florencia,Venecia,Lisboa,Oporto,Aveiro]
Copy 
var mArrayCitiesEs = ['Barcelona','Sevilla','Valencia'];
var mArrayCitiesIt = ['Roma','Florencia','Venecia'];
var mArrayCitiesPt = ['Lisboa','Oporto','Aveiro'];

var mArrAllCities = mArrayCitiesEs.concat(mArrayCitiesIt, mArrayCitiesPt);

console.log(`Spain cities array: ${mArrayCitiesEs}`);
console.log(`Italy cities array: ${mArrayCitiesIt}`);
console.log(`Portugal cities array: ${mArrayCitiesPt}`);
console.log(`Join all arrays: ${mArrAllCities}`);
Spain cities array: Barcelona,Sevilla,Valencia
Italy cities array: Roma,Florencia,Venecia
Portugal cities array: Lisboa,Oporto,Aveiro
Join all arrays: Barcelona,Sevilla,Valencia,Roma,Florencia,Venecia,Lisboa,Oporto,Aveiro

  • Concatenating values to an array

Copy 
var mArrayCities = ['Barcelona','Roma'];

var mArrAllCities = mArrayCities.concat('Berlin', ['Paris','Oporto']);

console.log(`Cities array: ${mArrayCities}`);
console.log(`Join array with values: ${mArrAllCities}`);
Cities array: Barcelona,Roma
Join array with values: Barcelona,Roma,Berlin,Paris,Oporto

  • Concatenating nested arrays

Copy 
var mArrayCities = [['Roma']];
var mArrayCities2 = ['Barcelona',['Berlin', 'Valencia']];

var mArrAllCities = mArrayCities.concat(mArrayCities2);

console.log(`Cities array: ${mArrayCities}`);
console.log(`Cities array2: ${mArrayCities2}`);
console.log(`Join array with values: ${mArrAllCities}`);
Cities array: Roma
Cities array2: Barcelona,Berlin,Valencia
Join array with values: Roma,Barcelona,Berlin,Valencia

Parameters

If all parameters are omitted, concat returns a shallow copy of the existing array on which it is called.

7.2 Array.entries()

The entries() method returns a new Array Iterator object that contains the key/value pairs for each index in the array.

entries() METHOD
Syntax array.entries()
Parameters No parameters.
Return A new Array iterator object.

This method does not change the original array.

Copy 
var mArrFruits = ['pineapple', 'apple', 'banana', 'orange'];

var mIterator = mArrFruits.entries();

console.log(mIterator.next().value);
console.log(mIterator.next().value);
console.log(mIterator.next().value);
console.log(mIterator.next().value);
[0, pineapple]
[1, apple]
[2, banana]
[3, orange]

  • Using a for…of loop

Copy 
<xsql-script>
    <body>
        <set name='m_Fruits'>
            <array>
                <string>Pinaple</string>
                <string>Apple</string>
                <string>Banana</string>
                <string>Orange</string>
            </array>
        </set>

        <struct.declare type='oEntry'>
            <field name='key'   type='integer' />
            <field name='value' type='string' />
        </struct.declare>

        <set name="m_Iterator"><array /></set>
        <set name="m_counter">0</set>

        <iterator name="m_fruit">
            <in>
                <m_Fruits />
            </in>
            <do>
                <set name='m_row'>
                    <struct type='oEntry'>
                        <get name='m_counter'/>
                        <get name='m_fruit'/>
                    </struct>
                </set>
                <array.add name='m_Iterator'>
                    <m_row />
                </array.add>  
                <set name='m_counter'>
                    <add>
                        <m_counter/>
                        1
                    </add>
                </set>
            </do>     
        </iterator>

        <iterator name="m_itera">
            <in>
                <m_Iterator />
            </in>
            <do>
                <println> [<m_itera.key /> , <m_itera.value />] </println>
            </do>     
        </iterator>
    </body>
</xsql-script>
[0 , Pinaple]
[1 , Apple]
[2 , Banana]
[3 , Orange]
Copy 
var mArrFruits = ['pineapple', 'apple', 'banana', 'orange'];

var mIterator = mArrFruits.entries();

for (let mFruit of mIterator) {
  console.log(mFruit);
}
[0, pineapple]
[1, apple]
[2, banana]
[3, orange]

7.3 Array.filter()

The filter() method creates a new array with all elements that pass the test implemented by the provided function.

filter() METHOD
Syntax mArrayName.filter(function(currentValue, index, array), thisArg)
Parameters

function: to be run for test each element of the array. Return a true value to keep the element, or false otherwise.

currentValue: The current element being processed in the array.

index: The index of the current element being processed in the array.

array: The array filter was called.

thisArg: Value to use as this when executing function.
Return A new array with the elements that pass the test. If no elements pass the test, an empty array will be returned.
Copy 
var mArrWords = ['gift', 'limit', 'cards', 'exuberant', 'destruction', 'future'];

function __checkWord(pStrWord) {
  if (pStrWord.length > 6){
  return pStrWord;
  }
}

let mArrResult = mArrWords.filter(__checkWord);

console.log(`Result array : ${mArrResult}`);
Result array : exuberant,destruction

7.4 Array.forEach()

The forEach() method executes a provided function once for each array element.

forEach() METHOD
Syntax mArrayName.forEach(function(currentValue, index, array),thisArg)
Parameters

function: to execute on each element.

currentValue: the current element being processed in the array

index: the index of currentValue in the array.

array: the array forEach() was called upon.

thisArg: Value to use as this when executing function.
Return Undefined.

forEach() does not mutate the array on which it is called. (However, function may do so).

Copy 
function __checkAges(pIntAge) {
    if (pIntAge > 18) {
        console.log(`Age old: ${pIntAge}`);
    }
}

var mArrAges = [45, 4, 9, 16, 25];

mArrAges.forEach(__checkAges);
Age old: 45
Age old: 25

7.5 Array.indexOf()

The indexOf() method searches the first occurrence of an element value,that is passed as an argument, at an array and returns its position.

indexOf() METHOD
Operador Xsql <array.indexOf name='array_name' >
Syntax mArrayName.indexOf(item, start)
Parameters

item: element to locate in the array.

start: Optional. Where to start the search. Negative values will start at the given position counting from the end, and search to the end.
Return The first index of the element in the array; -1 if not found.
Copy 
<xsql-script>
    <body>
        <array name='m_cities'>
            <string>Barcelona</string>
            <string>Paris</string>
            <string>Roma</string>
            <string>Paris</string>
        </array>

        <set name='m_position'>
            <array.indexOf name='m_cities'>
                <string>Paris</string>
            </array.indexOf>
        </set>

        <println>Paris position: [<m_position />]</println>
    </body>
</xsql-script>
Paris position: [1]
Copy 
var mArrayCities = ['Barcelona','Paris','Roma','Paris'];
var mIntPosition = null;

mIntPosition = mArrayCities.indexOf('Paris');

console.log(`Paris position: [${mIntPosition}]`);
Paris position: [1]

7.6 Array.isArray()

The Array.isArray() method determines whether the passed value is an Array.

isArray() METHOD
Syntax Array.isArray(value)
Parameters

value: the value to be checked.
Return A Boolean. Returns true if the value is an Array; otherwise, false.
Copy 
var mArrNumbers = [2,3,5,7,11];
var mStrNumbers = 'two, three, five';
var mStrValue = null;

console.log(`mArrNumbers is array: [${Array.isArray(mArrNumbers)}]`);
console.log(`mStrNumbers is array: [${Array.isArray(mStrNumbers)}]`);
console.log(`mStrValue is array: [${Array.isArray(mStrValue)}]`);
mArrNumbers is array: [true]
mStrNumbers is array: [false]
mStrValue is array: [false]

7.7 Array.join()

The join() method creates and returns a new string by concatenating all of the elements in an array, separated by commas or a specified separator string.

indexOf() METHOD
Operador Xsql <array.join separator='separator' >
Syntax mArrayName.join(separator)
Parameters

separator: Specifies a string to separate each pair of adjacent elements of the array. If omitted, the array elements are separated with a comma (",").

Return A string with all array elements joined.

If separator is an empty string, all elements are joined without any characters in between them.

Copy 
<xsql-script>
    <body>
        <array name='m_cities'>
            <string>Barcelona</string>
            <string>Paris</string>
            <string>Roma</string>
        </array>

        <set name='m_result'>
            <array.join separator=' - '>
                <m_cities />
            </array.join>
        </set>

        <println>Cities: <m_result /></println>
    </body>
</xsql-script>
Cities: Barcelona - Paris - Roma
Copy 
var mArrayCities = ['Barcelona','Paris','Roma'];

var mStrResult = mArrayCities.join(' - ');

console.log(`Cities: ${mStrResult}`);
Cities: Barcelona - Paris - Roma

Element

If an array element is undefined, null or an empty array [], it is converted to an empty string.

7.8 Array.keys()

The keys() method returns a new Array Iterator object that contains the keys for each index in the array.

keys() METHOD
Syntax mArrayName.keys()
Parameters

No parameters.
Return A new Array iterator object.
Copy 
<xsql-script>
    <body>
        <set name='m_cities'>
            <array>
            <string>Barcelona</string>
            <string>Paris</string>
            <string>Roma</string>
            </array>
        </set>

        <set name='m_length'>
            <array.size name='m_cities' />
        </set>

        <set name='m_length'>
            <sub>
                <m_length/>
                1
            </sub>
        </set>

        <set name='m_iterator'>
            <array/>
        </set>
        
        <for name='i' start='0' end='${m_length}' step='1'>
            <do>
                <array.add name='m_iterator'>
                    <i />
                </array.add>  
                <println>Key : [<i/>] </println>
            </do>
        </for>
    </body>
</xsql-script>
Key : [0] 
Key : [1] 
Key : [2]
Copy 
var mArrayCities = ['Barcelona','Paris','Roma'];

const mIterator = mArrayCities.keys();

for (const key of mIterator) {
  console.log(`key : [${key}] `);
}
key : [0] 
key : [1] 
key : [2]

7.9 Array.lastIndexOf()

The lastIndexOf() method searches the last occurrence of an item value,that is passed as an argument, at an array and returns its position.

lastIndexOf() METHOD
Syntax mArrayName.lastIndexOf(item, start)
Parameters

item: item to locate in the array.

start: Optional. Where to start the search. Negative values will start at the given position counting from the end, and search to the beginning

Return The last index of the element in the array; -1 if not found.
Copy 
<xsql-script>
    <body>
        <set name='m_cities'>
            <array>
                <string>Barcelona</string>
                <string>Paris</string>
                <string>Roma</string>
                <string>Paris</string>
            </array>
        </set>

        <set name='m_city_to_search'>
            <string>Paris</string>
        </set>

        <set name='m_position' type="integer">0</set>

        <set name='m_length'>
            <array.size name='m_cities' />
        </set>

        <set name='m_length'>
            <sub>
                <m_length/>
                1
            </sub>
        </set>
        
        <for name='i' start='0' end='${m_length}' step='1'>
            <do>
                <set name='m_city'>
                    <array.get name='m_cities'>
                        <number><i/></number>
                    </array.get>
                </set>

                <if>
                    <expr><eq> <m_city /><m_city_to_search /></eq></expr>
                    <then>
                        <set name='m_position'>
                            <i/>
                        </set>
                    </then>
                </if>
            </do>
        </for>
        <println>Paris position: [<m_position />]</println>   
    </body>
</xsql-script>
Paris position: [3]
Copy 
var mArrayCities = ['Barcelona','Paris','Roma','Paris'];
var mIntPosition = null;

mIntPosition = mArrayCities.lastIndexOf('Paris');

console.log(`Paris position: [${mIntPosition}]`);
Paris position: [3]

7.10 Array.map()

The map() method creates a new array of the results of calling a provided function on every element in the calling array.

map() METHOD
Syntax mArrayName.map(function(currentValue, index, array),thisArg)
Parameters

function: is called for every element of array, the returned value is added to newArray.

currentValue: the current element being processed in the array.

index: the index of the current element being processed in the array.

array: the array map was called upon.

thisArg: Value to use as this when executing function.
Return A new array with each element being the result of calling function
Copy 
function __lengthWord(word) {
  return word.length;
}

var mArrWords = ['gift', 'limit', 'cards', 'exuberant', 'destruction', 'future'];

const mArrResult = mArrWords.map(__lengthWord);

console.log(`Original array : ${mArrWords}`);
console.log(`Result array : ${mArrResult}`);
Original array : gift,limit,cards,exuberant,destruction,future
Result array : 4,5,5,9,11,6

7.11 Array.pop()

The pop() method removes the last element from an array and returns that element.

The pop() method changes the length of the array.

pop() METHOD
Operador Xsql <array.removeLast name='array_name' />
Syntax mArrayName.pop()
Parameters No parameters.
Return The removed element from the array
Copy 
<xsql-script>
    <body>
        <array name='m_cities'>
            <string>Barcelona</string>
            <string>Paris</string>
            <string>Roma</string>
        </array>

        <println>Array cities before remove element: <m_cities /></println>

        <array.removeLast name='m_cities' />

        <println>Array cities after remove element: <m_cities /></println>
    </body>
</xsql-script>
Array cities before remove element: [Barcelona,Paris,Roma]
Array cities after remove element: [Barcelona,Paris]
Copy 
var mArrayCities = ['Barcelona','Paris','Roma'];

console.log(`Array cities before remove element: ${mArrayCities}`);

mArrayCities.pop();

console.log(`Array cities after remove element: ${mArrayCities}`);
Array cities before remove element: Barcelona,Paris,Roma
Array cities after add element: Barcelona,Paris

7.12 Array.push()

The push() method adds one or more elements to the end of an array and returns the new length of the array.

The push() method changes the length of the array.

push() METHOD
Operador Xsql <array.add name='array_name' />
Syntax mArrayName.push(element1, element2, ..., elementX)
Parameters The element(s) to add to the end of the array.
Return A Number, representing the new length of the array
Copy 
<xsql-script>
    <body>
        <array name='m_cities'>
            <string>Barcelona</string>
            <string>Paris</string>
            <string>Roma</string>
        </array>

        <println>Array cities before add element: <m_cities /></println>

        <array.add name='m_cities'>
            <string>Budapest</string>
        </array.add>

        <println>Array cities after add element: <m_cities /></println>
    </body>
</xsql-script>
Array cities before add element: [Barcelona,Paris,Roma]
Array cities after add element: [Barcelona,Paris,Roma,Budapest]
Copy 
var mArrayCities = ['Barcelona','Paris','Roma'];

console.log(`Array cities before add element: ${mArrayCities}`);

var mIntLength = mArrayCities.push('Budapest');

console.log(`Array cities after add element: ${mArrayCities}`);
console.log(`New length of array : ${mIntLength}`);
Array cities before add element: Barcelona,Paris,Roma
Array cities after add element: Barcelona,Paris,Roma,Budapest
New length of array : 4

7.13 Array.reduce()

The reduce() method executes a reducer function (that you provide) on each element of the array, resulting in single output value.

The reduce() method does not change the original array.

reduce() METHOD
Syntax mArrayName.reduce(function(accumulator, currentValue, index, array),initialValue)
Parameters

function: to execute on each element in the array (except for the first, if no initialValue is supplied).

accumulator: the accumulator accumulates return values of the function.

currentValue: the current element being processed in the array.

index: the index of the current element being processed in the array.

array: the array reduce() was called upon.

initialValue:a value to use as the first argument to the first call of the function.
Return Returns the accumulated result from the last call of the function
Copy 
var mArraNumbers = [1, 2, 3, 4];

function __functionAdd(accumulator, currentValue) {
  return accumulator + currentValue;
}

console.log(`1 + 2 + 3 + 4 = ${mArraNumbers.reduce(__functionAdd)}`);
console.log(`5 + 1 + 2 + 3 + 4 : ${mArraNumbers.reduce(__functionAdd, 5)}`);
1 + 2 + 3 + 4 : 10
5 + 1 + 2 + 3 + 4 : 15

7.14 Array.reduceRight()

The reduceRight() method applies a function against an accumulator and each value of the array (from right-to-left) to reduce it to a single value

reduce() METHOD
Syntax mArrayName.reduceRight(function(accumulator, currentValue, index, array),initialValue)
Parameters

function: to execute on each value in the array.

accumulator: the value previously returned in the last invocation of the function.

currentValue: the current element being processed in the array.

index: the index of the current element being processed in the array.

array: the array reduceRight() was called upon.

initialValue:a value to use as the first argument to the first call of the function.
Return Returns the accumulated result from the last call of the function
Copy 
var mArraNumbers = [[0, 1], [2, 3], [4, 5]];

var mArrResult = [[0, 1], [2, 3], [4, 5]].reduceRight(
  (accumulator, currentValue) => accumulator.concat(currentValue)
);

console.log(`mArraNumbers : ${mArraNumbers}`);
console.log(`mArrResult : ${mArrResult}`);
mArraNumbers : 0,1,2,3,4,5
mArrResult : 4,5,2,3,0,1

7.15 Array.reverse()

The reverse() method reverses an array in place. The first array element becomes the last, and the last array element becomes the first.

The reverse() this method will change the original array.

reverse() METHOD
Operador Xsql <array.reverse name='array_name' />
Syntax mArrayName.reverse()
Parameters No parameters.
Return The reversed array.
Copy 
<xsql-script>
    <body>
        <array name='m_cities'>
            <string>Barcelona</string>
            <string>Paris</string>
            <string>Roma</string>
        </array>

        <println>Array cities before reverse: <m_cities /></println>

        <array.reverse name='m_cities' />

        <println>Array cities after reverse: <m_cities /></println>
    </body>
</xsql-script>
Array cities before reverse: [Barcelona,Paris,Roma]
Array cities after reverse: [Roma,Paris,Barcelona]
Copy 
var mArrayCities = ['Barcelona','Paris','Roma'];

console.log(`Array cities before reverse: ${mArrayCities}`);

mArrayCities.reverse();

console.log(`Array cities after reverse: ${mArrayCities}`);
Array cities before reverse: Barcelona,Paris,Roma
Array cities after reverse: Roma,Paris,Barcelona

7.16 Array.shift()

The shift() method removes the first element from an array and returns that removed element.

The shift() method changes the length of the array.

shift() METHOD
Operador Xsql <array.removeFirst name='array_name' />
Syntax mArrayName.shift()
Parameters No parameters.
Return The removed element from the array.
Copy 
<xsql-script>
    <body>
        <array name='m_cities'>
            <string>Barcelona</string>
            <string>Paris</string>
            <string>Roma</string>
        </array>

        <println>Array cities before remove element: <m_cities /></println>

        <array.removeFirst name='m_cities' />

        <println>Array cities after remove element: <m_cities /></println>
    </body>
</xsql-script>
Array cities before remove element: [Barcelona,Paris,Roma]
Array cities after remove element: [Paris,Roma]
Copy 
var mArrayCities = ['Barcelona','Paris','Roma'];

console.log(`Array cities before remove element: ${mArrayCities}`);

mArrayCities.shift();

console.log(`Array cities after remove element: ${mArrayCities}`);
Array cities before remove element: Barcelona,Paris,Roma
Array cities after remove element: Paris,Roma

7.17 Array.slice()

The slice() method returns a copy of a portion of an array into a new array selected from start to end (end not included) where start and end represent the index of items in that array.

slice() METHOD
Operador Xsql <array.clone />
Syntax mArrayName.slice(start, end)
Parameters

start: Optional. An integer that specifies where to start the selection.

end: Optional. An integer that specifies where to end the selection.
Return A new array containing the extracted elements.

The slice() method not remove any elements from the source array, it does creates a new array.

Copy 
<xsql-script>
    <body>
        <array name='m_cities'>
            <string>Barcelona</string>
            <string>Paris</string>
            <string>Roma</string>
        </array>

        <set name='m_cities_clone'>
            <array.clone name='m_cities' />
        </set>

        <println>Original array: <m_cities /></println>
        <println>Copie array: <m_cities_clone /></println>
    </body>
</xsql-script>
Original array: [Barcelona,Paris,Roma]
Copie array: [Barcelona,Paris,Roma]
Copy 
var mArrayCities = ['Barcelona','Paris','Roma'];

var mArrCitiesClone = mArrayCities.slice();

console.log(`Original array: ${mArrayCities}`);
console.log(`Copied array: ${mArrCitiesClone}`);
Original array: Barcelona,Paris,Roma
Copied array: Barcelona,Paris,Roma

Start is optional:

  • If start is undefined, slice starts from the index 0.
  • If start is greater than the index range of the sequence, an empty array is returned.
End is Optional:
  • If end is omitted, slice extracts through the end of the sequence (array.length).
  • If end is greater than the length of the sequence, slice extracts through to the end of the sequence (array.length).

Copy a portion of an existing array

Copy 
var mArrayCities = ['Barcelona','Paris','Roma','Budapest'];

var mArrCitiesClone = mArrayCities.slice(1,3);

console.log(`Original array: ${mArrayCities}`);
console.log(`Copied array: ${mArrCitiesClone}`);
Original array: Barcelona,Paris,Roma,Budapest
Copied array: Paris,Roma

A negative index can be used, indicating an offset from the end of the sequence. slice(-2) extracts the last two elements in the sequence.

Copy 
var mArrayCities = ['Barcelona','Paris','Roma','Budapest'];

var mArrCitiesClone = mArrayCities.slice(-2);

console.log(`Original array: ${mArrayCities}`);
console.log(`Copie array: ${mArrCitiesClone}`);
Original array: Barcelona,Paris,Roma,Budapest
Copie array: Roma,Budapest

A negative index can be used, indicating an offset from the end of the sequence. slice(2,-1) extracts the third element through the second-to-last element in the sequence.

Copy 
var mArrayCities = ['Barcelona','Paris','Roma','Budapest'];

var mArrCitiesClone = mArrayCities.slice(1,-1);

console.log(`Original array: ${mArrayCities}`);
console.log(`Copie array: ${mArrCitiesClone}`);
Original array: Barcelona,Paris,Roma,Budapest
Copie array: Paris,Roma

7.18 Array.some()

The some() method tests whether at least one element in the array passes the test implemented by the provided function. It returns a Boolean value.

The some() method does not change the original array.

some() METHOD
Syntax mArrayName.some(function(currentValue, index, array),thisArg)
Parameters

function: to test for each element.

currentValue: the current element being processed in the array.

index: the index of the current element being processed in the array.

array: the array some() was called upon.

thisArg: a value to use as this when executing function.
Return A Boolean. Returns true if any of the elements in the array pass the test, otherwise it returns false.
Copy 
function __checkEven(pIntNumber){
    return pIntNumber % 2 === 0;
}

var mArrNumbers = [1, 2, 3, 5, 7];

console.log(`An element is even : ${mArrNumbers.some(__checkEven)}`);
An element is even : true

7.19 Array.sort()

The sort() method sorts the elements of an array in place and returns the sorted array.

The default sort order is ascending.

sort() METHOD
Operador Xsql <array.sort name='array_name' />
Syntax mArrayName.sort(compareFunction)
Parameters compareFunction: Optional. A function that defines an alternative sort order.
Return The sorted array.
Copy 
<xsql-script>
    <body>
        <array name='m_cities'>
            <string>Paris</string>
            <string>Roma</string>
            <string>Barcelona</string>
        </array>

        <println>Array cities before sorted: <m_cities /></println>

        <array.sort name='m_cities' />

        <println>Array cities after sorted: <m_cities /></println>
    </body>
</xsql-script>
Array cities before sorted: [Paris,Roma,Barcelona]
Array cities after sorted: [Barcelona,Paris,Roma]
Copy 
var mArrayCities = ['Paris','Roma','Barcelona'];

console.log(`Array cities before sorted: ${mArrayCities}`);

mArrayCities.sort();

console.log(`Array cities after sorted: ${mArrayCities}`);
Array cities before sorted: Paris,Roma,Barcelona
Array cities after sorted: Barcelona,Roma,Paris

Compare Function

The function should return a negative, zero, or positive value, depending on the arguments, like:

function(a, b){return a-b}

When the method compares two values, it sends the values to the compare function, and sorts the values according to the returned (negative, zero, positive) value.

Example:

When comparing 40 and 100, the sort() method calls the compare function(40,100).

The function calculates 40-100, and returns -60 (a negative value).

The sort function will sort 40 as a value lower than 100.

Sort numbers in an array in descending order:

Copy 
var mArrNumbers = [40, 100, 1, 5, 25, 10];

console.log(`Array numbers before sorted: ${mArrNumbers}`);

mArrNumbers.sort(function(a, b){return b-a});

console.log(`Array numbers after sorted: ${mArrNumbers}`);
Array numbers before sorted: 40,100,1,5,25,10
Array numbers after sorted: 100,40,25,10,5,1

7.20 Array.splice()

The splice() method changes the contents of an array by removing or replacing existing elements and/or adding new elements in place.

The splice() method changes the original array.

splice() METHOD
Operador Xsql <array.remove name='array_name' />
Syntax mArrayName.splice(start, deleteCount, element1, ....., elementX)
Parameters

index: Required. The index at which to start changing the array.

howmany: Optional. An integer indicating the number of elements in the array to remove from start.

compareFunction: Optional. The elements to add to the array, beginning from start.
Return The sorted array.
Copy 
<xsql-script>
    <body>
        <array name='m_cities'>
            <string>Barcelona</string>
            <string>Paris</string>
            <string>Roma</string>
        </array>

        <println>Array cities before remove element: <m_cities /></println>

        <array.remove name='m_cities'>
            <string>1</string>
        </array.remove>

        <println>Array cities after remove element: <m_cities /></println>
    </body>
</xsql-script>
Array cities before remove element: [Barcelona,Paris,Roma]
Array cities after remove element: [Barcelona,Roma]
Copy 
var mArrayCities = ['Barcelona','Paris','Roma'];

console.log(`Array cities before remove element: ${mArrayCities}`);

mArrayCities.splice(1, 1);

console.log(`Array cities after remove element: ${mArrayCities}`);
Array cities before remove element: Barcelona,Paris,Roma
Array cities after remove element: Barcelona,Roma

Remove items from an index position

Copy 
var mArrayCities = ['Barcelona','Paris','Roma','Budapest'];

console.log(`Array cities before remove element: ${mArrayCities}`);

mArrayCities.splice(1, 2);

console.log(`Array cities after remove element: ${mArrayCities}`);
Array cities before remove element: Barcelona,Paris,Roma,Budapest
Array cities after remove element: Barcelona,Budapest

7.21 Array.toString()

The toString() method returns a string representing the specified array and its elements.

toString() METHOD
Syntax mArrayName.toString()
Parameters No parameters.
Return A string representing the elements of the array
Copy 
var mArrFruits = ["Banana", "Orange", "Apple", "Mango"];
var mStrFruits = mArrFruits.toString();

console.log(`Array become to string: ${mStrFruits}`);
Array become to string: Banana,Orange,Apple,Mango

7.22 Array.unshift

The unshift() method adds one or more elements to the beginning of an array and returns the new length of the array.

unshift() METHOD
Syntax mArrayName.unshift(element[1], element[2], ... element[n])
Parameters The element(s) to add to the begining of the array.
Return A Number, representing the new length of the array.
Copy 
<xsql-script>
    <body>
        <set name='m_cities'>
            <array>
                <string>Barcelona</string>
                <string>Paris</string>
                <string>Roma</string>
            </array>
        </set>

        <println>Array cities before add element: <m_cities /></println>

        <!--Save the elements of the original in a temporal array-->
        <set name='m_cities_temp'>
            <array.clone name='m_cities' />
        </set>

        <!--Clean the original array-->
        <array.clear name='m_cities' />

        <!--Add the element at the first position-->
        <array.add name='m_cities'>
            <string>Budapest</string>
        </array.add>

        <!--Loop through the m_cities_temp array to add at the original array-->
        <iterator name='m_city_temp'>
            <in>
                <m_cities_temp/>
            </in>
            <do>
                <array.add name='m_cities'>
                   <m_city_temp />
                </array.add>    
            </do>
        </iterator>

        <!--Clean the temporal array-->
        <array.clear name='m_cities_temp' />

        <println>Array cities after add element: <m_cities /></println>
    </body>
</xsql-script>
Array cities before add element: [Barcelona,Paris,Roma]
Array cities after add element: [Budapest,Barcelona,Paris,Roma]
Copy 
var mArrayCities = ['Barcelona','Paris','Roma'];
        
console.log(`Array cities before add element: ${mArrayCities}`);
        
mArrayCities.unshift('Budapest');
        
console.log(`Array cities after add element: ${mArrayCities}`);
Array cities before add element: Barcelona,Paris,Roma
Array cities after add element: Budapest,Barcelona,Paris,Roma