Introduction:
Functions are very important and useful in any
programming language as they make the code reusable. A function is a block
of code which will be executed only if it is called.
If you have a few lines of code
that needs to be used several times, you can create a function including the repeating lines of code and then call the function wherever
you want.
What
is Function?
A function
is a group of reusable code which can be called
anywhere in your program.
This eliminates the need of writing the same code repeatedly.
It helps programmers in writing modular codes.
Functions allow a programmer to divide
a big program into a number of small and manageable functions.
Declaring A Function:
Before we
use a function, we need to define it. The most common way to define a function
in JavaScript is by using the function
keyword, followed by a unique function name,
a list of parameters (that might be empty),
and a statement block
surrounded by curly braces.
Syntax:
function
functionname(parameter-list)
{
statements
}
Adding An Arguments:
We can pass some arguments
to the function.
Syntax:
function
functionname(argument1, argument2,….. argumentn)
{
statements
}
Returning A Value From A Function:
A JavaScript function can have an optional
return statement.
This is required if you want to return
a value from
a function. This statement should be the last statement in a function.
The return value is either stored in variable or directly display in browser
Conclusion:
We understand that how implement functions JavaScript.
JavaScript
to check vowels from given string-using function.
<html>
<head>
<script
type="text/javascript"> var count = 0;
var name = prompt("Please enter
your name"); for (var i=0;i<name.length;i++)
{
if(name[i] == "a" || name[i] == "e" || name[i] == "i" || name[i] == "o" || name[i] == "u"){
count = count + 1;
}
}
document.write("Hello
" + name + "...!!! Your name has " + count + "
vowels.");
</script>
</head>
<body>
</body>
</html>
Output: Hello abhi...!!! Your name has 2 vowels.
-----------------------------------------------------------------------------------------------------
JavaScript Return Value using function.
<html>
<head>
<script type="text/javascript"> function returnSum(first, second)
{
var sum = first + second; return sum;
}
var firstNo = 78; var secondNo = 22;
document.write(firstNo
+ " + " + secondNo + " = " + returnSum(firstNo,secondNo));
</script>
</head>
<body>
</body>
</html>
Output: 78 + 22 = 100
-----------------------------------------------------------------------------------------------------
B]
<html>
<head>
<script
type="text/javascript"> function
returnSum(first) {
var square =
first * first; return square;
}
var firstNo =
16;
document.write("Square"
+ " = " + returnSum(firstNo));
</script>
</head>
<body>
</body>
</html>
Output: Square = 256
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