Java Script: Array Reference

Array

Arrays are a way of storing multiple values together.
Arrays are best use to store similar values.

Creating Array

var myArray = [];

var myArray = new Array(Number of Element);

var myArray = new Array(Element 1, Element 2,...);

Looping Array

Easiest way to access all elements.

var myArray = [1,2,3]; 

for(var index in myArray){

     document.write(myArray[index]);

}

Result

123

Traditional programming approach. Can only access contiguous array.

var myArray = [1,2,3]; 

for(var index=0; index < myArray.length; index++){

     document.write(myArray[index]);

}

Result

123

Looping through the array and consuming it contents. Starting with the last element

var myArray = [1,2,3]; 
while(myArray.length){
     document.write(myArray.pop());
}

Result

321

Looping through the array and consuming it contents. Starting from the first element

var myArray = [1,2,3]; 
while(myArray.length){
     document.write(myArray.shift());
}

Result

123

Other Cool methods

array.concat(array[,array]*) 

Join two or more array and return the joined array.
Example

var myArrayA = [1,3,5];

var myArrayB = ['a','b','c'];

var combineArray = myArrayA.concat(myArrayB);

Result

myArrayA = [1,3,5]
myArrayB = ['a','b','c'];
combineArray = [1,3,5,'a','b','c'];

array.join()

concatenate all element of an array into a string.

Example

var myArray = ['a','b','c'];
var myString = myArray.join();

Result

myArray = ['a','b','c'];
myString = "abc";

array.pop()

remove the last element of the array.

array.push()

insert an element to the end of the array;

array.shift()

remove the first element of the array.

array.unshift()

insert an element at the beginning of the array.

Example

var myArray = ['a','b','c','d','e'];
var myPop = myArray.pop();
var myShift = myArray.shift();
myArray.unshift(myPop);
myArray.push(myShift);

Result

myArray = ['e','b','c','d','a'];
myPop = 'e'
myShift = 'a'

array.reverse() 

Reverses the order of the elements in the array

Example

var myArray = ['a','b','c','d','e'];
myArray.reverse();

Result

myArray = ['e','d','c','b','a'];

array.slice(start, end)

Create an array from a part of the current array. Beginning at start and end at end.

array.splice(index, element to remove [, new element]*);

remove number of element at position index, and insert new element at index. Returning removed elements.

Example

var myArray = ['a','b','c','d','e'];
var mySliceArray = myArray.slice(1,3);
var myRemoveElement = myArray.splice(1,3,'z','y');

Result

myArray = ['a','z','y','e']
mySliceArray = ['b','c'];
myRemoveElement = ['b','c','d'];

array.sort(function(a,b){return a>b}?)

Sort the array by the provided function.
The default comparison function is function(a,b){return a>b}.

Example

var myArray = [4,3,1,2];
myArray.sort();

Result

myArray = [1,2,3,4];

Java Script: debugging

The best tools for debugging JavaScript would be firebug from Firefox.

You can get firebug at  http://getfirebug.com/

If your using other browsers, have no fear there is firebug lite, it a JavaScript base firebug. It on all major browser.



What is so awesome about this tool?

• Inject JavaScript directly on to the website page with out going to the editor.
• Inspect properties and paramaters of JavaScript object.

Beside JavaScript FireBug have loads of other feature, goto http://getfirebug.com/whatisfirebug for more details.

FireBug Layout,

1. Input box for writing JavaScript
2. Out put of evaluate JavaScript
3. Expand the 1.Java Script Input, for writing easier JavaScript.

Clicking on 3 will result in the following window.

Here you can have all the fun in the world.


TIPS
You can undo and redo with in the input area.
to undo press ctrl+z or redo press ctrl+y

Keep text editor open, while writing and testing code with fire bugs, so you would have some history.