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What Is A Function

A function is automated method , procedure or module to do some job with automated manner with just call it .It may be set of commands , arguments , conditions and calculations .

It is set of instruction or code that performs a specific task and can be processed independently.

Note:  functions main features are , it works only when it calls .

For example functions code only executed when it is called . When functions are not called then codes contain place it stay neutral . It executes only when it is called .

function working
function working

Syntax

Functions syntax may vary according the programming language , but working of functions is same is all programming languages.

Working

When a program passes control to a function , then it perform that task and returns control to the instruction following the calling instruction.

Format And Syntax of  JavaScript functions

function name (arguments)
{
code contained in this section executed ,when function is called
};

Example

<button onclick="helloMessage()">Run Function</button>
<script>
function helloMessage()
{
alert("Hello ! you just clicked the button");
}
</script>

In this example a function is created to display alert box . It is called in button tag . when user click on the “button” , code is executed and an alert message box is displayed

Check This Function’s Working

Why Required and Usage

Functions are reusable . When you create , you can call it many times in your application of webpage ,when you need it .

The most important reason to use of functions is make program handling easier  as only a small part of the program is dealt with at a time.