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Arrays in Javascript

Arrays are list-like objects that are used for storing multiple values in a single variable.

Javascript arrays do not have fixed types or lengths.

let dogs = ['Beagle', 'Corgi', 'Labrador Retriever'];

Array Properties

Property Description
length Returns the number of elements inside the array

Instance methods

Array.prototype.concat()

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

Array.prototype.copyWithin()

Copies a sequence of array elements within the array.

Array.prototype.entries()

Returns a new Array Iterator object that contains the key/value pairs for each index in the array.

Array.prototype.every()

Returns true if every element in this array satisfies the testing function.

Array.prototype.fill()

Fills all the elements of an array from a start index to an end index with a static value.

Array.prototype.filter()

Returns a new array containing all elements of the calling array for which the provided filtering function returns true.

Array.prototype.find()

Returns the found element in the array, if some element in the array satisfies the testing function, or undefined if not found.

Array.prototype.findIndex()

Returns the found index in the array, if an element in the array satisfies the testing function, or -1 if not found.

Array.prototype.forEach()

Calls a function for each element in the array.

Array.prototype.includes()

Determines whether the array contains a value, returning true or false as appropriate.

Array.prototype.indexOf()

Returns the first (least) index of an element within the array equal to an element, or -1 if none is found.

Array.prototype.join()

Joins all elements of an array into a string.

Array.prototype.keys()

Returns a new Array Iterator that contains the keys for each index in the array.

Array.prototype.lastIndexOf()

Returns the last (greatest) index of an element within the array equal to an element, or -1 if none is found.

Array.prototype.map()

Returns a new array containing the results of calling a function on every element in this array.

Array.prototype.pop()

Removes the last element from an array and returns that element.

Array.prototype.push()

Adds one or more elements to the end of an array, and returns the new length of the array.

Array.prototype.reduce()

Apply a function against an accumulator and each value of the array (from left-to-right) as to reduce it to a single value.

Array.prototype.reduceRight()

Apply a funciton against an accumulator> and each value of the array (from right-to-left) as to reduce it to a single value.

Array.prototype.reverse()

Reverses the order of the elements of an array in place. (First becomes the last, last becomes first.)

Array.prototype.shift()

Removes the first element from an array and returns that element.

Array.prototype.slice()

Extracts a section of the calling array and returns a new array.

Array.prototype.some()

Returns true if at least one element in this array satisfies the provided testing function.

Array.prototype.sort()

Sorts the elements of an array in place and returns the array.

Array.prototype.splice()

Adds and/or removes elements from an array.

Array.prototype.toLocaleString()

Returns a localized string representing the array and its elements. Overrides the Object.prototype.toLocaleString() method.

Array.prototype.toString()

Returns a string representing the array and its elements. Overrides the Object.prototype.toString() method.

Array.prototype.unshift()

Adds one or more elements to the front of an array, and returns the new length of the array.

Array.prototype.values()

Returns a new Array Iterator object that contains the values for each index in the array.

For more information, please visit MDN