Variables are used to store data values. Use "var" keyword befor the variable name Example: var x; to declare javascript variables. (=) is called equal sign that is used to assign values to variables.
Variables are containers for storing data values.
There are two types of variables in JavaScript :
Let’s see a simple example of JavaScript variable:
JavaScript global variable:
A JavaScript global variable is accessible from any function. A variable i.e. declared outside the function or declared with window object is known as global variable.
Example:
Example:
var a = 10; // a is variable name
There are two types of variables in JavaScript :
- local variable and
- global variable.
There are some rules while declaring a JavaScript variable (also known as identifiers):
- Variable name must start with a letter like (a to z or A to Z), underscore( _ ), or dollar( $ ) sign.
- After first letter we can use digits (0 to 9), Example variable2.
- JS variables are case sensitive, Example a and A are different variables.
Correct JavaScript variables:
var a = 100;
var _variable="Bangla";
Incorrect JavaScript variables:
var 521=10;
var *ba=450;
<html>
<body>
<h2>JavaScript Variables Example</h2>
</body>
</html>
<script>
var a = 50;
var b = 5;
var c = a + b;
document.write(c);
</script>
Result:
JavaScript Variables Example
55
JavaScript local variable:
Local variable is declared inside block or function in javascrupt. Local variable is accessible within the function or block only.
Example:
<script>
function xyz(){
var a = 100; // JavaScript local variable
}
</script>
or
<script>
If(a<b){
var a = 15; // JavaScript local variable
}
</script>
A JavaScript global variable is accessible from any function. A variable i.e. declared outside the function or declared with window object is known as global variable.
Example:
<html>
<body>
<script>
var global_variable= 100; //global variable
function abc(){
document.writeln(global_variable);
}
function xyz(){
document.writeln(global_variable);
}
abc(); //call JavaScript function
xyz();
</script>
</body>
</html>
Project Source Code:
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Variables</h2>
<h4>variables are used to store data values.</h4> <h4>JavaScript always use the <b style="color: red; font-weight: bold">var</b> example: var x; keyword to declare javascript variables.</h4>
<h4>An <b style="color: red; font-weight: bold">equal sign (=)</b> is used to assign values to variables. </h4>
<p>Here x is a variable. Then assigned the value to variable x</p>
<p id="example"></p>
</body>
</html>
<script type="text/javascript">
var x = 10 + 12; // here = is used to assign the value of variable x and used var keyword to declare the variable document.getElementById("example").innerHTML = "The value of Variable x is ="+x;
</script>
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