Javascript : Mathematical Methods
11:32 PM - Posted by Vipin C - 1 comments
In addition to the mathematical constants that can be accessed from the Math object there are also several methods available.

The following example uses the round() method of the Math object to round a number to the nearest integer:

 document.write(Math.round(4.7));

The code above will result in the following output:
5

The following example uses the random() method of the Math object to return a random number between 0 and 1:

 document.write(Math.random());

The code above can result in the following output:
0.6936874867631697 

The following example uses the floor() and random() methods of the Math object to return a random number between 0 and 10:

 document.write(Math.floor(Math.random()*11));

The code above can result in the following output:
0


Javascript : Mathematical Constants
11:31 PM - Posted by Vipin C - 0 comments
JavaScript provides eight mathematical constants that can be accessed from the Math object. These are: E, PI, square root of 2, square root of 1/2, natural log of 2, natural log of 10, base-2 log of E, and base-10 log of E.
You may reference these constants from your JavaScript like this:

Math.E
Math.PI
Math.SQRT2
Math.SQRT1_2
Math.LN2
Math.LN10
Math.LOG2E
Math.LOG10E


Javascript Math Object
11:30 PM - Posted by Vipin C - 0 comments
The Math object allows you to perform mathematical tasks.

Math Object

The Math object allows you to perform mathematical tasks.
The Math object includes several mathematical constants and methods.

Syntax for using properties/methods of Math:

 var pi_value=Math.PI;
var sqrt_value=Math.sqrt(16);

Note: Math is not a constructor. All properties and methods of Math can be called by using Math as an object without creating it.



Javascript Boolean Object
11:29 PM - Posted by Vipin C - 0 comments
The Boolean object is used to convert a non-Boolean value to a Boolean value (true or false).

The Boolean object represents two values: "true" or "false".

The following code creates a Boolean object called myBoolean:

 var myBoolean=new Boolean();

Note: If the Boolean object has no initial value or if it is 0, -0, null, "", false, undefined, or NaN, the object is set to false. Otherwise it is true (even with the string "false")!
All the following lines of code create Boolean objects with an initial value of false:

 var myBoolean=new Boolean();
var myBoolean=new Boolean(0);
var myBoolean=new Boolean(null);
var myBoolean=new Boolean("");
var myBoolean=new Boolean(false);
var myBoolean=new Boolean(NaN);

And all the following lines of code create Boolean objects with an initial value of true:


var myBoolean=new Boolean(true);
var myBoolean=new Boolean("true");
var myBoolean=new Boolean("false");
var myBoolean=new Boolean("Richard");



Javascript : Modify Values in an Array
11:28 PM - Posted by Vipin C - 0 comments
To modify a value in an existing array, just add a new value to the array with a specified index number:

 myCars[0]="Opel";

Now, the following code line:

 document.write(myCars[0]);

will result in the following output:
Opel


javascript : Access an Array
11:27 PM - Posted by Vipin C - 0 comments
You can refer to a particular element in an array by referring to the name of the array and the index number. The index number starts at 0.

The following code line:

 document.write(myCars[0]);

will result in the following output:
 
Saab


Javascript : Create an Array
11:26 PM - Posted by Vipin C - 0 comments
The following code creates an Array object called myCars:

var myCars=new Array();

There are two ways of adding values to an array (you can add as many values as you need to define as many variables you require).

1:

 var myCars=new Array();
myCars[0]="Saab";
myCars[1]="Volvo";
myCars[2]="BMW";

You could also pass an integer argument to control the array's size:

 var myCars=new Array(3);
myCars[0]="Saab";
myCars[1]="Volvo";
myCars[2]="BMW";

2:

 var myCars=new Array("Saab","Volvo","BMW");

Note: If you specify numbers or true/false values inside the array then the type of variables will be numeric or Boolean instead of string.


Javascript Array Object
11:25 PM - Posted by Vipin C - 0 comments

What is an Array?

An array is a special variable, which can hold more than one value, at a time.
If you have a list of items (a list of car names, for example), storing the cars in single variables could look like this:

cars1="Saab";
cars2="Volvo";
cars3="BMW";

However, what if you want to loop through the cars and find a specific one? And what if you had not 3 cars, but 300?

The best solution here is to use an array!

An array can hold all your variable values under a single name. And you can access the values by referring to the array name.
Each element in the array has its own ID so that it can be easily accessed.


Javascript : Date Object
6:39 AM - Posted by Vipin C - 0 comments

Create a Date Object

The Date object is used to work with dates and times. 
The following code create a Date object called myDate:

var myDate=new Date()

Note: The Date object will automatically hold the current date and time as its initial value!

Set Dates

We can easily manipulate the date by using the methods available for the Date object.
In the example below we set a Date object to a specific date (14th January 2010):

var myDate=new Date();
myDate.setFullYear(2010,0,14);

And in the following example we set a Date object to be 5 days into the future:

var myDate=new Date();
myDate.setDate(myDate.getDate()+5);

Note: If adding five days to a date shifts the month or year, the changes are handled automatically by the Date object itself!

Compare Two Dates

The Date object is also used to compare two dates.
The following example compares today's date with the 14th January 2010:

var myDate=new Date();
myDate.setFullYear(2010,0,14);
var today = new Date();

if (myDate>today)
  {
  alert("Today is before 14th January 2010");
  }
else
  {
  alert("Today is after 14th January 2010");
  }


Javascript : String Object
6:36 AM - Posted by Vipin C - 0 comments
The String object is used to manipulate a stored piece of text.

Examples of use:

The following example uses the length property of the String object to find the length of a string:

var txt="Hello world!";
document.write(txt.length);

The code above will result in the following output:
12

The following example uses the toUpperCase() method of the String object to convert a string to uppercase letters:

var txt="Hello world!";
document.write(txt.toUpperCase());

The code above will result in the following output:
HELLO WORLD!


javascript : Methods
6:34 AM - Posted by Vipin C - 0 comments
Methods are the actions that can be performed on objects.
In the following example we are using the toUpperCase() method of the String object to display a text in uppercase letters:

 <script type="text/javascript">
var str="Hello world!";
document.write(str.toUpperCase());
</script>		 

The output of the code above will be:
HELLO WORLD!


Javascript : Properties
6:32 AM - Posted by Vipin C - 0 comments
Properties are the values associated with an object.
In the following example we are using the length property of the String object to return the number of characters in a string:



<script type="text/javascript">
var txt="Hello World!";
document.write(txt.length);
</script>


The output of the code above will be:
12


Javascript : Object Oriented Programming
6:31 AM - Posted by Vipin C - 0 comments
JavaScript is an Object Oriented Programming (OOP) language. An OOP language allows you to define your own objects and make your own variable types.
However, creating your own objects will be explained later, in the Advanced JavaScript section. We will start by looking at the built-in JavaScript objects, and how they are used. The next pages will explain each built-in JavaScript object in detail.
Note that an object is just a special kind of data. An object has properties and methods.


JavaScript Objects Introduction
6:30 AM - Posted by Vipin C - 0 comments
JavaScript is an Object Oriented Programming (OOP) language.
An OOP language allows you to define your own objects and make your own variable types.