Declare Variables Using Var In JavaScript

The var keyword has been to declare variables since 1995.

JavaScript variables can be declared in 4 ways. Automatically, using var, let or const.

Var is used to declare variables in a function or global scope.

Variable Declaration

Glossary:

Scope

Refers to region of the code where variable is accessible.

Global Scope

Variables declared outside function or block are accessible anywhere.

Block Scope

Variables declared within block such as if or for statement are only accessible in that local scope.

Function Scope

Variables declared within function are only accessible in that local scope.

Initialization

Variables are initialized with a default value.

Redeclaration

Variables are redeclared in the same scope.

Declaring Variables

Var Variable Declaration

Name	Description	Example
var	Declares function scope or global scope with optional initialization	var num = 1;
Name	Description	Example

Var Variable Declaration Snippet

// OjamboShop.com Learning JavaScript Var Variable Declaration Tutorial
// Global Scope
var num1;
num1 = 1;
console.log(num1);
// Accessible Outside Block
if (true) {
	console.log(num1);
	var num2 = 2;
}
console.log(num2);
// Redeclare And Reassign Variable
var num1 = 11;
var num2 = 22;
console.log(num1);
console.log(num2);
// Hoisting 
{
	console.log(num3);
	var num3 = 3;
}
console.log(num3);

Usage

You can use any IDE or text editor and the web browser to compile and execute JavaScript code. For this tutorial, the OjamboShop.com Learning JavaScript Course Web IDE was used to input and compile JavaScript code for the var variable declaration.

Open Source

JavaScript follows the ECMAScript standard and is licensed under the W3C Software License by web browser vendors and runtime environment vendors. This allows commercial use, modification, distribution, and allows making derivatives proprietary.

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Conclusion:

JavaScript makes it easy to declare variables. Use var to declare function or global scoped variables with the optional initialization.

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