JavaScript Data Types:
JavaScript Data Types are the types of values that can be represented and manipulated by JavaScript.
JavaScript Data Types List:
1. Numbers. 2. Strings. 3. Boolean. 4. Null. 5. Undefined. 6. Object. 7. Array. 8. RegExp.
JavaScript variables:
The variable is the name of a reserved memory location. In JavaScript, the var keyword is used to declare a variable.
Rules for declaring a JavaScript variable:
1. JavaScript variable name must begin with a letter, underscore, or dollar sign. 2. JavaScript variable names are case-sensitive. 3. JavaScript reserved keywords like abstract, boolean, etc can’t be used as JavaScript variable names.
JavaScript variable scope:
1. Local variable. 2. Global variable.
JavaScript Local variable:
A variable defined inside a function or block of JavaScript code is known as a local variable. It can be accessed only within that function or block.
JavaScript Local Variable Example:
<html>
<head>
<script>
function showNumber(){
//local variable
var num=10;
document.write(num);
}
showNumber();
</script>
</head>
<body>
</body>
</html>
Try it:
JavaScript Global variable:
A variable defined outside a function or block of JavaScript code is known as a global variable. It can be accessed anywhere in JavaScript code
JavaScript Global Variable Example:
<script>
<html>
<head>
<script>
//Global variable
var num=10;
function showNumber(){
document.writeln(num);
}
function displayNumber(){
document.writeln(num);
}
showNumber();
displayNumber();
</script>
</head>
<body>
</body>
</html>
Try it:
