Create a Variable: var

To create a variable using var, we use the following syntax:

1var variableName;

Variable Naming Rules:

• Variable names must start with a letter, underscore, or dollar sign.
• They can contain letters, numbers, underscores, or dollar signs.
• They are case-sensitive, so myVariable and myvariable are different variables.

Assigning a Value to a Variable

We can assign a value to a variable during declaration or later in the code. Example:

1var message;
2message = "Hello, world!";
3
4var greeting = "Welcome!"; // We can initialize and declare a variable in a single line of code.

Variable usage

Once we have assigned a value to a variable, we can use it in our code. Example:

1var num1 = 10;
2var num2 = 5;
3var sum = num1 + num2;
4console.log(sum); // Output: 15