Arrays

• Indexed arrays are zero-based.
• Arrays are objects.

• Trailing commas at the end of array literals are ignored.
• An array literal is a type of object initializer.

Indexed array

var numArray = new Array(1);
numArray[0] = new Array(2);
numArray[0][0] = "red";
numArray[0][1] = "round";

// Array literal
var colors = ["orange", "blue", "green"];
var animals = ["lion", , "zebra"];        // animals[1] is undefined.
var fish = ["bass", , ,];                 // This array contains only 1 element.

("one,two,three").split(",")              // Equivalent to ["one", "two", "three"]

Associative array

// Array literal (JSON syntax)
var assocArray = {lemon:"yellow", lime:"green"};

var a = 1, b = 2, myArray = {a:a, b:b};           // Equivalent to {a:1, b:2}

Properties

length

• The number of elements in the array.

Methods

concat

• Joins two arrays and returns a new array.

var myArray = arr1.concat(arr2);

join

• Joins all elements of an array into a string.

var myStr = myArray.join(", ");

pop

• Removes and returns the last element from an array.

push

• Adds one or more elements to the end of an array and returns the last element added.

reverse

• Reverses the order of the array elements.

shift

• Removes and returns the first element from an array.

slice

• Returns a portion of an array and as a new array.

splice

• Adds and/or removes elements from an array.

sort

• Sorts the array elements alphabetically.
• To sort numeric elements, a helper function must be provided:

function sortNumber(a, b) { return a - b; }        // Ascending order
[3,1,4,2].sort( sortNumber )                       // [1, 2, 3, 4]

[3,1,4,2].sort( function(a, b){return a - b;} )    // [1, 2, 3, 4]

unshift

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