ARRAYS IN JAVASCRIPT

ARRAY:

• Array allows us to store multiple values in a single variable.
  
• Array values are accessed using index variables(also called as subscripts).
  
• Can have single,two ,three dimensions etc.
  
• Single dimension refers to rows
  
• Multiple dimensions refers to both rows and columns.
  

SYNTAX:

var array-name = [item1, item2, ...]; 

Example:

var a=[“apple”,”mango”,”grapes”];
(or)
var a = new Array("apple", "mango", "grapes");

Accessing the elements of an array:

An array element can be accessed by using index value.

Example:

var name = a[0];

In this example first element of the array is stored in the variable called 'name'

Example:

a[0] = "PineApple";

This example modifies the arrays first element into Pineapple instead of apple.

Tip:

[0] is the first element in an array. [1] is the second. Array indexes start with 0.

NEW KEYWORD:

Following example also creates an Array, and assigns values to it:

var a = new Array("apple", "mango", "grapes");

LOOPING ARRAY ELEMENTS:

• The best way to access the elements of an array is by using LOOP.
• The best Loop to use is FOR-NEXT

Example:

var index;
var fruits = ["Banana", "Orange", "Apple", "Mango"];
for (index = 0; index < fruits.length; index++) {
    text += fruits[index];
}

Arrays are objects:

• Arrays are a special type of objects. The typeof operator in JavaScript returns "object" for arrays.
• Arrays use numbers to access its "elements"
• Objects use names to access its "members"

Example:

var person = ["sakthi", "vel", 34];

person[0] returns sakthi

Example:

var person = {firstName:"sakthi", lastName:”vel", age:34};

person.firstName returns sakthi

Array properties:

• constructor-Returns a reference to the array function that created the object.
• input-This property is only present in arrays created by regular expression matches.
• index-This property represents the zero-based index of the match in the string
• length-Reflects the number of elements in an array.

Array Methods:

• concat()-Returns a new array comprised of this array joined with other array(s) and/or value(s).
• every()-Returns true if every element in this array satisfies the provided testing function.
• filter()-Creates a new array with all of the elements of this array for which the provided filtering function returns true.
• sort()-Sorts the elements of an array.
• reverse()-Reverses the order of the elements of an array -- the first becomes the last, and the last becomes the first.
• join()-Joins all elements of an array into a string.
• indexOf()-Returns the first (least) index of an element within the array equal to the specified value, or -1 if none is found.
• push()-Adds one or more elements to the end of an array and returns the new length of the array.
• pop()-Removes the last element from an array and returns that element.