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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