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JavaScript Global Variable

A JavaScript global variable is declared outside the function or declared with window object. It can be accessed from any function.

Let’s see the simple example of global variable in JavaScript.

<script>
var value=50;//global variable
function a(){
alert(value);
}
function b(){
alert(value);
}
</script>

Test it Now

Declaring JavaScript global variable within function

To declare JavaScript global variables inside function, you need to use window object. For example:

Now it can be declared inside any function and can be accessed from any function. For example:

function m(){
window.value=100;//declaring global variable by window object
}
function n(){
alert(window.value);//accessing global variable from other function
}

Test it Now

Internals of global variable in JavaScript

When you declare a variable outside the function, it is added in the window object internally. You can access it through window object also. For example:

var value=50;
function a(){
alert(window.value);//accessing global variable 
}

Next TopicJavaScript Data Types

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JavaScript Global Variable

Declaring JavaScript global variable within function

Internals of global variable in JavaScript