Variable in Javascript

The concept of variable is very essential in every programming language, at the end of this article you should be able to understand

1. What is a Variable?

2. 3 methods to declare variables in Javascript.

3. Scope

4. Function, Global, and Block Scope.

what is a Variable?

A variable is a storage location that is used to hold a value, imagine you have a shelf in your room where you keep different boxes and inside those boxes 📦 you store different items in them, the box is like the variable and the items are the values the box hold.

You can think of the process of storing a letter in the box as assigning value to a variable, you can also equate the process of accessing the value of a variable as opening the box and looking at what is inside.

var box = letter1;
// WHERE box IS THE VARIABLE
// "letter1" IS THE VALUE STORED IN THE VARIABLE
// VAR IS THE KEYWORD FOR DECLARING box AS A VARIABLE.

And then you could access the value of the box variable like this

console.log(box); //output : letter1

Just like you can put different things in the box that you keep on your shelf, you can also assign different values to a variable in JavaScript. You could, for example, change the value of the box variable to the letter 3.

Methods of declaring a variable in Javascript

Variables in javascript can be declared using VAR, LET, AND CONST keywords, we would take a look at them individually.

Var Keyword

var: This is the traditional way of declaring variables in JavaScript. It is used to declare variables that are either Function Scope (that is they are only accessible within the function they exist) or Global Scope (that is they are accessible anywhere in the code).

var x = 10; //Global scope

function () {
    var y = 11;
} // function scoped

Let Keyword

let: This is a newer way of declaring variables in JavaScript, introduced in ECMAScript 6 (ES6). It is used to declare variables that are Block Scope, meaning that the variables are only available within the block in which they are defined.

let y = 20;

Const Keyword

const: This is also a newer way of declaring variables in JavaScript, introduced in ECMAScript 6 (ES6). It is used to declare read-only variables, meaning that the variable's value cannot be reassigned.

const z = 30;

Conclusion

It's important to note that var is function-scoped, while let and const are block-scoped. This means that variables declared with var can be accessed within the entire function in which they are declared, while variables declared with let and const are only accessible within the block in which they are defined.

Happy Reading!!!

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