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JavaScript Functions

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Java script Function is nothing but it is a reusable code-block that is execute when the function is called.

JavaScript Functions

     

In this article you will learn about the JavaScript functions.

What is JavaScript Function?
Java script Function is nothing but it is a reusable code-block that is execute when the function is called. Function is defined in the head section of the code. The syntax of JavaScript function is as follows:

function fname(prameter1,parameter2, ...)
{
   JavaScript code 1
  JavaScript code 2
   ....
}

While defining JavaScript function its important to remember that the keyword function should be in lowercase other wise JavaScript won't understand it as function. If you write function in uppercase the code will generate error. In the JavaScript semicolon is optional but its better to put semi-colon as part of best practices. All the java script code are written inside the curly  braces.

Example:
 <html>
  <head>
  <script language="javascript">
   function showmessage(){
  alert("How are you");
   }
   </script>
  </head>
  <body>
  <form>
  <input type="button" value="Click Here!" 
  onclick="showmessage()" >
  </form>
  </body>
</html>

Function starts with the function keyword and code of the function is enclosed in {..} brackets.  Functions are written inside the head section of the html document, because function does not execute when the page loads. The alert function displays the message "How are you", when you clicked on the button ("Click Here")..  

To test the program click here.

What is the use of JavaScript Functions:
The java Script Function is very useful in writing the JavaScript code. It is used to group many JavaScript codes under one name. For example you can write a function to validate email address.

Built-in functions

JavaScript provides many built in functions that ease the development of JavaScript programs. Here are the list of the built-in JavaScript functions:

JavaScript Build in Function Function Description
alert() The alert() built-in function displays the alert dialog box.
confirm() The confirm() built-in function display the confirmation dialog box. and ask the user to determine from the two option .
focus() The focus() built -in  function built the pointed object active and put the curser on the text field.
indexOf()  
prompt() The prompt() built -in function display the prompt dialog box. Inquiring the user for input.
select() The select() built -in function used  to select the pointed object.
write() The write() built in function used to write something on the document.
   

Function arguments: Through variable you can pass argument to function. The out put of the function looks on  the arguments given by you .

Example:

<html> 
<head> 
<script language="javascript"> 
function myfunction(text) 

confirm(text) 

</script> 
</head> 

<body> 
<form> 
<input type="button" 
onclick="myfunction('Do you want to delete it!')" 
value="Delete"> 

<input type="button" 
onclick="myfunction('Do you want to save it!')" 
value="Save"> 
</form> 
</body> 
</html> 

 

 


 

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Posted on: May 23, 2009

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Comments:6
Mukesh Kumar
May 30, 2011
mouse event

all mouse event code give me
Abu Bakar
June 11, 2011
Comment

This tips are so useful for bigneers
Inayat Ullah
July 11, 2011
BS(CS)Hon's

I am the student of computer scienc and i want to become a PHP programmer.
kiruba
September 21, 2011
javascript programming

very nice
Prasanna Kumar
September 22, 2012
How to use select()

I request to please provide an example for select() in javascript
lol
December 6, 2012
lol

step down
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