Arrays – It is an ordered collection of values with each value is called an element, having a numeric position in the array called its index. JavaScript arrays may be of any type and elements of the same array can be of different types.
Array creation – An array is created with a comma-separated list of elements within square brackets. Array can be empty with no elements or with elements as
var blank = []; // Empty array
var odd = [1, 3, 5, 7]; // Array with elements
Array object – Another way to create an array is with the Array() constructor by calling it with
- No arguments: var a = new Array();
- A single numeric argument, of length: var a = new Array(10);
- Two or more elements: var a = new Array(5, 4, 3, 2, 1, “testing, testing”);
Element access – To access an element of array use the [] operator with array name and index in the square brackets as arrayname[index]. This form can be used to read or write value at the specified index.
Array methods – Various array methods are discussed below:
- concat(array1 [, array2 [, …]]) – Creates a new array by joining two or more arrays
- filter(callback [, contextObject]) – Filters the elements of an array using a callback function
- join([separator]) – Join the elements of the array into a string using a separator
- pop() – Removes the last element of the array and returns that element
- push(element0 [, element1 [, …]]) – Appends one or more elements to the end of the array and returns the new length of the array
- reduce(callback [, initialValue]) – Reduce the array to a single value using a callback function from left-to-right
- reverse() – Reverses the order of the elements in the array
- shift() – Removes the first element of the array and returns that element
- slice(offset [, length]) – Extracts a section of the array and returns a new array containing the extracted elements
- sort([compare_function]) – Sorts the array optionally using a callback function
- splice(offset , length [, element1 [, element2 [, …]]]) – Replaces elements from the array with something else
- toString() – Returns a string representation of the array
- unshift(element0 [, element1 [, …]]) – Prepend one or more elements to the front of the array and returns the new length of the array
- valueOf() – Returns the primitive value of the array