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VARIABLES
A variable is a memory reference to a stored value. It is used to name any data so that it can be
accessed later in the script. Variables can be declared and initialised in a script as follows:
let: It declares a variable that can be changed later. It’s limited to the block it’s in (like a loop
or function).
let x = 5; // Here, you can change the value of variable x.
x = 10;
var: It declares a variable that can be changed and redeclared. It works globally or within a
function, but it’s less commonly used now.
var y = 20;
var y = 30; // You can redeclare it.
Here, you can redeclare the value of variable y.
const: It declares a constant that can’t be changed. Once a value is set, it stays the same.
const z = 15;
z = 20; // Error! You can't change a const value.
Here, the error occurs. You cannot change the value of a const variable.
When naming variables, the following rules must be followed:
A variable can contain letters, numbers, dollar signs ($) and underscores (_).
Spaces are not allowed in variable names.
JavaScript keywords cannot be used as variable names.
A variable name cannot start with a numeral (0-9). It must begin with a letter or an underscore.
For example, 123test is invalid, but _123test is valid.
Variable names are case-sensitive. For example, Name and name are different variables.
Variable names must be shorter than 255 characters.
Code
3 Create a web page to demonstrate the use of variables in JavaScript.
<!DOCTYPE HTML>
<HTML>
<HEAD>
<TITLE>Variables</TITLE>
</HEAD>
<BODY>
<SCRIPT>
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