In this tutorial we will learn How To Change Variable Value in JavaScript. We can use JavaScript function to change the variable value by reassigning it a new value. We can also do this outside of function.
Table of Contents
HTML Code
HTML Code is given below, in this code we have a paragraph tag to display the new value of the variable.
<!DOCTYPE html>
<html>
<head>
<title>JavaScript Variable Change Value</title>
</head>
<body>
<p id="output"></p>
<script src="script.js"></script>
</body>
</html>
JavaScript Code
Take a look at the JavaScript code, in this code we have a variable with value = 100. This value is then changed to 200 inside a user defined function.
Function is then called to change the value. Value will not change without the function call because a JavaScript function is only executed on function call.
getElementById() method is used to select the paragraph tag and innerHTML property is used to display the changed value of variable.
<script>
var variable = 100;
function changeValue()
{
variable = 200;
}
changeValue();
document.getElementById('output').innerHTML = variable;
</script>
Variable declared outside function is global variable.
Variable declared inside function is local variable.
We can also do this without function.
<script>
var variable = 100;
variable = 200; //simple reassignment
document.getElementById('output').innerHTML = variable;
</script>
Demo
Video Tutorial
Watch video tutorial on How To Change Variable Value with JavaScript.