Var in JavaScript

Var:

• The var keyword was used in all JavaScript code before 2015.
• While it was the only way to declare variables in older versions of JavaScript.
• Variables declared with var have Function Scope.

Using var, we can declare the variable and initialize it later.

<script>
var subject;
</script>

But, accessing the variable before initialization shows Undefined.

What is Undefined?

• undefined is a special value in JavaScript that means a variable has been declared, but no value has been assigned to it yet.

Re-initializing a value for var variable is possible.

<script>
 var subject="Maths";
 subject="Science"
 console.log(subject);
</script>

Output:

Science

Re-Declaring the var variable is possible.

<script>
var subject="Maths";
var subject="Science"
console.log(subject);
</script>

Output:

Science

Hoisting in var:

Hoisting means JavaScript moves the declaration of a variable to the top of its scope before executing the code.

When a variable is declared using var, only the declaration is hoisted, not the value assignment.

<script>
console.log(a);
var a = 10;
</script>

Output:

Undefined

Excited to continue learning and building with JavaScript!