Variables

In JavaScript, a variable is a symbolic name that represents a value. Variables are used to store and manipulate data within a program. Unlike some other programming languages, JavaScript is dynamically typed, meaning that variables can hold values of any data type, and the data type of a variable can change over time.

 

Here’s a basic definition of variables in JavaScript:

 

Declaration: Variables are declared using the var, let, or const keyword, followed by the variable name. For example:

 

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var x;

let y;

const z = 10;

Assignment: After declaring a variable, you can assign a value to it using the assignment operator =. For example:

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x = 5;

y = "Hello";

Initialization: You can also declare and initialize a variable in a single step. This involves declaring the variable and assigning a value to it simultaneously. For example:

 

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var a = 10;

let b = "World";

Naming: Variable names (identifiers) can consist of letters, digits, underscores, and dollar signs. They must begin with a letter, underscore (_), or dollar sign ($). Variable names are case-sensitive.

 

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var firstName;

var myVariable;

var _myVariable;

var $myVariable;

Data Types: JavaScript variables can hold values of various data types, including numbers, strings, booleans, arrays, objects, functions, and more. The data type of a variable is determined dynamically based on the value assigned to it.

 

JavaScript is a loosely typed language, meaning you don’t need to specify the data type of a variable explicitly. However, you can use the typeof operator to check the data type of a variable at runtime.