Array

Overview

The javascript Array implementation. It is a collection of items kept by index, providing typical array API. The index is a integer (>= 0) or a string representing such an integer.

For more information see: Array (MDN).

Properties Summarized

Type	Name	Summary
Object	[index]	Get an element by index.
Number	length	Get the length of the array.

Methods Summarized

Type	Name	Summary
Array	concat(value1)	Returns a new array comprised of this array joined with other array(s) and/or value(s).
Array	concat(value1, value2)	Returns a new array comprised of this array joined with other array(s) and/or value(s).
Array	concat(value1, value2, valueN)	Returns a new array comprised of this array joined with other array(s) and/or value(s).
Array	copyWithin(target)	Shallow copies part of an array to another location in the same array and returns it without modifying its length
Array	copyWithin(target, start)	Shallow copies part of an array to another location in the same array and returns it without modifying its length
Array	copyWithin(target, start, end)	Shallow copies part of an array to another location in the same array and returns it without modifying its length
Boolean	every(callback)	Runs a function on items in the array while that function is returning true.
Boolean	every(callback, thisObject)	Runs a function on items in the array while that function is returning true.
Array	fill(value)	Changes all elements in an array to a static value, from a start index (default 0) to an end index (default array.
Array	fill(value, start)	Changes all elements in an array to a static value, from a start index (default 0) to an end index (default array.
Array	fill(value, start, end)	Changes all elements in an array to a static value, from a start index (default 0) to an end index (default array.
Array	filter(callback)	Runs a function on every item in the array and returns an array of all items for which the function returns true.
Array	filter(callback, thisObject)	Runs a function on every item in the array and returns an array of all items for which the function returns true.
Object	find(callback)	Returns the value of the first element in the provided array that satisfies the provided testing function.
Number	findIndex(callback)	Returns the index of the first element in the provided array which satisfies the provided testing function.
void	forEach(callback)	Runs a function (callback) on every item in the array.
void	forEach(callback, thisObject)	Runs a function (callback) on every item in the array.
Array	from(value)	Creates a new, shallow-copied Array instance from an iterable or array-like object.
Array	from(value, mapFunction, thisObject)	Creates a new, shallow-copied Array instance from an iterable or array-like object.
Boolean	includes(searchElement)	Determines whether an array includes a certain value among its entries, returning true or false as appropriate.
Boolean	includes(searchElement, start)	Determines whether an array includes a certain value among its entries, returning true or false as appropriate.
Number	indexOf(searchElement)	Returns the first index at which a given element can be found in the array, or -1 if it is not present.
Number	indexOf(searchElement, fromIndex)	Returns the first index at which a given element can be found in the array, or -1 if it is not present.
Boolean	isArray(obj)	Checks whether an object is an array or not.
String	join(delimiter)	Puts all elements in the array into a string, separating each element with the specified delimiter
Number	lastIndexOf(searchElement)	Returns the last index at which a given element can be found in the array, or -1 if it is not present.
Number	lastIndexOf(searchElement, fromIndex)	Returns the last index at which a given element can be found in the array, or -1 if it is not present.
Array	map(callback)	Runs a function on every item in the array and returns the results in an array.
Array	map(callback, thisObject)	Runs a function on every item in the array and returns the results in an array.
Array	of(value)	Ccreates a new Array instance from a variable number of arguments.
Object	pop()	Pops the last string off the array and returns it.
Number	push(value1)	Mutates an array by appending the given elements and returning the new length of the array.
Number	push(value1, value2)	Mutates an array by appending the given elements and returning the new length of the array.
Number	push(value1, value2, valueN)	Mutates an array by appending the given elements and returning the new length of the array.
Object	reduce(f, initialValue)	Reduces the array to a single value by executing a provided function for each value of the array (from left-to-right).
Array	reverse()	Puts array elements in reverse order.
Object	shift()	Decreases array element size by one by shifting the first element off the array and returning it.
Array	slice(begin)	The slice method creates a new array from a selected section of an array.
Array	slice(begin, end)	The slice method creates a new array from a selected section of an array.
Boolean	some(callback)	Runs a function on items in the array while that function returns false.
Boolean	some(callback, thisObject)	Runs a function on items in the array while that function returns false.
Array	sort()	Sorts the array elements in dictionary order or using a compare function passed to the method.
Array	sort(function)	Sorts the array elements in dictionary order or using a compare function passed to the method.
Array	splice(arrayIndex, length)	It is used to take elements out of an array and replace them with those specified.
Array	splice(arrayIndex, length, value1)	It is used to take elements out of an array and replace them with those specified.
Array	splice(arrayIndex, length, value1, value2)	It is used to take elements out of an array and replace them with those specified.
Array	splice(arrayIndex, length, value1, value2, valueN)	It is used to take elements out of an array and replace them with those specified.
Number	unshift(value1, value2, valueN)	Places element data at the start of an array.

Properties Detailed

[index]

Get an element by index.

Type Object

Sample

array[0]

length

Get the length of the array.

Type Number

Sample

array.length

Methods Detailed

concat(value1)

Returns a new array comprised of this array joined with other array(s) and/or value(s).

Parameters

• Object value1 ;

Returns: Array

Sample

array.concat();

concat(value1, value2)

Returns a new array comprised of this array joined with other array(s) and/or value(s).

Parameters

• Object value1 ;

• Object value2 ;

Returns: Array

Sample

array.concat();

concat(value1, value2, valueN)

Returns a new array comprised of this array joined with other array(s) and/or value(s).

Parameters

• Object value1 ;

• Object value2 ;

• Object valueN ;

Returns: Array

Sample

array.concat();

copyWithin(target)

Shallow copies part of an array to another location in the same array and returns it without modifying its length

Parameters

• Number target Zero-based index at which to copy the sequence to. If negative, target will be counted from the end.

Returns: Array

Sample

array.copyWithin(2);

copyWithin(target, start)

Shallow copies part of an array to another location in the same array and returns it without modifying its length

Parameters

• Number target Zero-based index at which to copy the sequence to. If negative, target will be counted from the end.

• Number start Zero-based index at which to start copying elements from. If negative, start will be counted from the end. If start is omitted, copyWithin will copy from index 0.

Returns: Array

Sample

array.copyWithin(2);

copyWithin(target, start, end)

Shallow copies part of an array to another location in the same array and returns it without modifying its length

Parameters

• Number target Zero-based index at which to copy the sequence to. If negative, target will be counted from the end.

• Number start Zero-based index at which to start copying elements from. If negative, start will be counted from the end. If start is omitted, copyWithin will copy from index 0.

• Number end Zero-based index at which to end copying elements from. copyWithin copies up to but not including end. If negative, end will be counted from the end.

Returns: Array

Sample

array.copyWithin(2);

every(callback)

Runs a function on items in the array while that function is returning true. It returns true if the function returns true for every item it could visit. The callback function is invoked with three arguments: the element value, the element index, the array being traversed.

Parameters

• Function callback ;

Returns: Boolean

Sample

function isNumber(value) { return typeof value == 'number'; }
var a1 = [1, 2, 3];
application.output(a1.every(isNumber));
var a2 = [1, '2', 3];
application.output(a2.every(isNumber));

every(callback, thisObject)

Runs a function on items in the array while that function is returning true. It returns true if the function returns true for every item it could visit. The callback function is invoked with three arguments: the element value, the element index, the array being traversed.

Parameters

• Function callback ;

• Array thisObject ;

Returns: Boolean

Sample

function isNumber(value) { return typeof value == 'number'; }
var a1 = [1, 2, 3];
application.output(a1.every(isNumber));
var a2 = [1, '2', 3];
application.output(a2.every(isNumber));

fill(value)

Changes all elements in an array to a static value, from a start index (default 0) to an end index (default array.length). It returns the modified array.

Parameters

• Object value Value to fill the array with.

Returns: Array

Sample

array.fill('test');

fill(value, start)

Changes all elements in an array to a static value, from a start index (default 0) to an end index (default array.length). It returns the modified array.

Parameters

• Object value Value to fill the array with.

• Number start Zero-based index at which to start filling.

Returns: Array

Sample

array.fill('test');

fill(value, start, end)

Changes all elements in an array to a static value, from a start index (default 0) to an end index (default array.length). It returns the modified array.

Parameters

• Object value Value to fill the array with.

• Number start Zero-based index at which to start filling.

• Number end Zero-based index at which to end filling.

Returns: Array

Sample

array.fill('test');

filter(callback)

Runs a function on every item in the array and returns an array of all items for which the function returns true. The callback function is invoked with three arguments: the element value, the element index, the array being traversed.

Parameters

• Function callback ;

Returns: Array

Sample

var a1 = ['a', 10, 'b', 20, 'c', 30];
var a2 = a1.filter(function(item) { return typeof item == 'number'; });
application.output(a2);

filter(callback, thisObject)

Runs a function on every item in the array and returns an array of all items for which the function returns true. The callback function is invoked with three arguments: the element value, the element index, the array being traversed.

Parameters

• Function callback ;

• Array thisObject ;

Returns: Array

Sample

var a1 = ['a', 10, 'b', 20, 'c', 30];
var a2 = a1.filter(function(item) { return typeof item == 'number'; });
application.output(a2);

find(callback)

Returns the value of the first element in the provided array that satisfies the provided testing function. If no values satisfy the testing function, undefined is returned. The callback function can invoked with three arguments: the element value, the element index(optional), the array being traversed (optional).

Parameters

• Function callback a testing function

Returns: Object the element which satisfies the function or undefined

Sample

var array1 = [5, 12, 8, 130, 44];
 var found = array1.find(function(element) { return element > 10});
 application.output(found); // prints 12

findIndex(callback)

Returns the index of the first element in the provided array which satisfies the provided testing function. If no values satisfy the testing function, -1 is returned. The callback function can invoked with three arguments: the element value, the element index (optional), the array being traversed (optional).

Parameters

• Function callback a testing function

Returns: Number the index of the first element which satisfies the function or -1

Sample

var array1 = [5, 12, 8, 130, 44];
 var found = array1.findIndex(function(element) { return element > 10});
 application.output(found); // prints 1

forEach(callback)

Runs a function (callback) on every item in the array. The callback function is invoked only for indexes of the array which have assigned values. The callback function is invoked with three arguments: the element value, the element index, the array being traversed.

Parameters

• Function callback ;

Returns: void

Sample

function printThemOut(element, index, array) {
		application.output("a[" + index + "] = " + element);
}
var a = ['a', 'b', 'c'];
a.forEach(printThemOut);

forEach(callback, thisObject)

Runs a function (callback) on every item in the array. The callback function is invoked only for indexes of the array which have assigned values. The callback function is invoked with three arguments: the element value, the element index, the array being traversed.

Parameters

• Function callback ;

• Object thisObject ;

Returns: void

Sample

function printThemOut(element, index, array) {
		application.output("a[" + index + "] = " + element);
}
var a = ['a', 'b', 'c'];
a.forEach(printThemOut);

from(value)

Creates a new, shallow-copied Array instance from an iterable or array-like object.

Parameters

• Object value An iterable or array-like object to convert to an array.

Returns: Array

Sample

var a = Array.from([1, 2, 3]);

from(value, mapFunction, thisObject)

Creates a new, shallow-copied Array instance from an iterable or array-like object.

Parameters

• Object value An iterable or array-like object to convert to an array.

• Function mapFunction Map function to call on every element of the array. If provided, every value to be added to the array is first passed through this function, and mapFunction's return value is added to the array instead.

• Object thisObject Value to use as this when executing mapFunction.

Returns: Array

Sample

var a = Array.from([1, 2, 3]);

includes(searchElement)

Determines whether an array includes a certain value among its entries, returning true or false as appropriate.

Parameters

• Object searchElement The value to search for.

Returns: Boolean

Sample

array.includes('test');

includes(searchElement, start)

Determines whether an array includes a certain value among its entries, returning true or false as appropriate.

Parameters

• Object searchElement The value to search for.

• Number start Zero-based index at which to start searching.

Returns: Boolean

Sample

array.includes('test');

indexOf(searchElement)

Returns the first index at which a given element can be found in the array, or -1 if it is not present.

Parameters

• Object searchElement ;

Returns: Number

Sample

var a = ['a', 'b', 'a', 'b', 'a'];
application.output(a.indexOf('b'));
application.output(a.indexOf('b', 2));
application.output(a.indexOf('z'));

indexOf(searchElement, fromIndex)

Returns the first index at which a given element can be found in the array, or -1 if it is not present.

Parameters

• Object searchElement ;

• Number fromIndex ;

Returns: Number

Sample

var a = ['a', 'b', 'a', 'b', 'a'];
application.output(a.indexOf('b'));
application.output(a.indexOf('b', 2));
application.output(a.indexOf('z'));

isArray(obj)

Checks whether an object is an array or not.

Parameters

• Object obj ;

Returns: Boolean

Sample

var a = [1, 2, 3];
application.output(Array.isArray(a)); //prints true
application.output(Array.isArray(23)); //prints false

join(delimiter)

Puts all elements in the array into a string, separating each element with the specified delimiter

Parameters

• String delimiter ;

Returns: String

Sample

var words = new Array("limit","lines","finish","complete","In","Out");
var jwords = words.join(";");

lastIndexOf(searchElement)

Returns the last index at which a given element can be found in the array, or -1 if it is not present. The array is searched backwards, starting at fromIndex.

Parameters

• Object searchElement ;

Returns: Number

Sample

var a = ['a', 'b', 'c', 'd', 'a', 'b'];
application.output(a.lastIndexOf('b'));
application.output(a.lastIndexOf('b', 4));
application.output(a.lastIndexOf('z'));

lastIndexOf(searchElement, fromIndex)

Returns the last index at which a given element can be found in the array, or -1 if it is not present. The array is searched backwards, starting at fromIndex.

Parameters

• Object searchElement ;

• Number fromIndex ;

Returns: Number

Sample

var a = ['a', 'b', 'c', 'd', 'a', 'b'];
application.output(a.lastIndexOf('b'));
application.output(a.lastIndexOf('b', 4));
application.output(a.lastIndexOf('z'));

map(callback)

Runs a function on every item in the array and returns the results in an array. The callback function is invoked with three arguments: the element value, the element index, the array being traversed.

Parameters

• Object callback ;

Returns: Array

Sample

var a = ['a', 'b', 'c'];
var a2 = a.map(function(item) { return item.toUpperCase(); });
application.output(a2);

map(callback, thisObject)

Runs a function on every item in the array and returns the results in an array. The callback function is invoked with three arguments: the element value, the element index, the array being traversed.

Parameters

• Object callback ;

• Array thisObject ;

Returns: Array

Sample

var a = ['a', 'b', 'c'];
var a2 = a.map(function(item) { return item.toUpperCase(); });
application.output(a2);

of(value)

Ccreates a new Array instance from a variable number of arguments.

Parameters

• Array value ;

Returns: Array

Sample

var a = Array.of(1, 2, 3);

pop()

Pops the last string off the array and returns it.

Returns: Object

Sample

var words = new Array("limit","lines","finish","complete","In","Out");
var lastword = words.pop();

push(value1)

Mutates an array by appending the given elements and returning the new length of the array.

Parameters

• Object value1 ;

Returns: Number

Sample

var words = new Array("limit","lines","finish","complete");
words.push("In","Out");

push(value1, value2)

Mutates an array by appending the given elements and returning the new length of the array.

Parameters

• Object value1 ;

• Object value2 ;

Returns: Number

Sample

var words = new Array("limit","lines","finish","complete");
words.push("In","Out");

push(value1, value2, valueN)

Mutates an array by appending the given elements and returning the new length of the array.

Parameters

• Object value1 ;

• Object value2 ;

• Object valueN ;

Returns: Number

Sample

var words = new Array("limit","lines","finish","complete");
words.push("In","Out");

reduce(f, initialValue)

Reduces the array to a single value by executing a provided function for each value of the array (from left-to-right).

Parameters

• Function f Function to execute on each element in the array, taking four arguments: -accumulator: accumulates the callback's return values; it is the accumulated value previously returned in the last invocation of the callback, or initialValue, if supplied (see below). -currentValue: the current element being processed in the array. -currentIndex (Optional): the index of the current element being processed in the array (starts at index 0, if an initialValue is provided, and at index 1 otherwise) -array (Optional): the array reduce() was called upon.

• Object initialValue Value to use as the first argument to the first call of the callback. If no initial value is supplied, the first element in the array will be used.

Returns: Object Object

Sample

var euros = [29.76, 41.85, 46.5];
var sum = euros.reduce( function(total, amount) {
  return total + amount
});

reverse()

Puts array elements in reverse order.

Returns: Array

Sample

var words = new Array("limit","lines","finish","complete","In","Out");
words.reverse();

shift()

Decreases array element size by one by shifting the first element off the array and returning it.

Returns: Object

Sample

var words = new Array("limit","lines","finish","complete","In","Out");
words.shift();

slice(begin)

The slice method creates a new array from a selected section of an array.

Parameters

• Object begin ;

Returns: Array

Sample

var words = new Array("limit","lines","finish","complete","In","Out");
var nwords1 = words.slice(3, 5);

slice(begin, end)

The slice method creates a new array from a selected section of an array.

Parameters

• Object begin ;

• Object end ;

Returns: Array

Sample

var words = new Array("limit","lines","finish","complete","In","Out");
var nwords1 = words.slice(3, 5);

some(callback)

Runs a function on items in the array while that function returns false. It returns true if the function returns true for any item it could visit. The callback function is invoked with three arguments: the element value, the element index, the array being traversed.

Parameters

• Function callback ;

Returns: Boolean

Sample

function isNumber(value) { return typeof value == 'number'; }
var a1 = [1, 2, 3];
application.output(a1.some(isNumber));
var a2 = [1, '2', 3];
application.output(a2.some(isNumber));

some(callback, thisObject)

Runs a function on items in the array while that function returns false. It returns true if the function returns true for any item it could visit. The callback function is invoked with three arguments: the element value, the element index, the array being traversed.

Parameters

• Function callback ;

• Array thisObject ;

Returns: Boolean

Sample

function isNumber(value) { return typeof value == 'number'; }
var a1 = [1, 2, 3];
application.output(a1.some(isNumber));
var a2 = [1, '2', 3];
application.output(a2.some(isNumber));

sort()

Sorts the array elements in dictionary order or using a compare function passed to the method.

Returns: Array

Sample

var words = new Array("limit","lines","finish","complete","In","Out");
words.sort();

sort(function)

Sorts the array elements in dictionary order or using a compare function passed to the method.

Parameters

• Function function ;

Returns: Array

Sample

var words = new Array("limit","lines","finish","complete","In","Out");
words.sort();

splice(arrayIndex, length)

It is used to take elements out of an array and replace them with those specified.

Parameters

• Object arrayIndex ;

• Object length ;

Returns: Array

Sample

var words = new Array("limit","lines","finish","complete","In","Out");
var nwords1 = words.splice(3, 2, "done", "On");

splice(arrayIndex, length, value1)

It is used to take elements out of an array and replace them with those specified.

Parameters

• Object arrayIndex ;

• Object length ;

• Object value1 ;

Returns: Array

Sample

var words = new Array("limit","lines","finish","complete","In","Out");
var nwords1 = words.splice(3, 2, "done", "On");

splice(arrayIndex, length, value1, value2)

It is used to take elements out of an array and replace them with those specified.

Parameters

• Object arrayIndex ;

• Object length ;

• Object value1 ;

• Object value2 ;

Returns: Array

Sample

var words = new Array("limit","lines","finish","complete","In","Out");
var nwords1 = words.splice(3, 2, "done", "On");

splice(arrayIndex, length, value1, value2, valueN)

It is used to take elements out of an array and replace them with those specified.

Parameters

• Object arrayIndex ;

• Object length ;

• Object value1 ;

• Object value2 ;

• Object valueN ;

Returns: Array

Sample

var words = new Array("limit","lines","finish","complete","In","Out");
var nwords1 = words.splice(3, 2, "done", "On");

unshift(value1, value2, valueN)

Places element data at the start of an array.

Parameters

• Object value1 ;

• Object value2 ;

• Object valueN ;

Returns: Number

Sample

var words = new Array("finish","complete","In","Out");
words.unshift("limit","lines");

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