📦 Training — Variables

📚 72 questions⏱ 15-20 min🏆 Instant feedback

📦 variables (Variables) JavaScript

definition using Variables in JavaScript

🎯 What You Will Learn in This Training

This interactive training will help you master Variables in JavaScript No :

✅ 68 Ali type , code, No
✅ var, let, const
✅ (Scope) (Hoisting)
✅ No variables
✅ operator reserved words variables
✅ Ability to retake the training to improve your level and reinforce concepts

❓ variable?

variable data memory. program, No "variable".

// Example: variable definition value
letuserName = "Ahmed";
letuserAge = 25;
letisActive = true;

🧠 1️⃣ definition Variables in JavaScript

✅ var ( )

Defining variables method
(scope) function
No using

✅ let

variable definition change No
solution ({})
variables variable

✅ const

variable definition No change definition
solution ({})
constant

// :
varoldWay = "method "; // ❌
letcounter = 0; // ✅ variable change
constAPI_KEY = "abc123"; // ✅ value constant
counter = 1; // ✅ (let)
// API_KEY = "xyz"; // ❌ False! const No change

🏷️ 2️⃣ Variables in JavaScript

// 1. (Numbers)
varage = 25;
varprice = 9.99;
// 2. string (Strings)
varname = "Ahmed";
varmessage = 'Hello!';
// 3. (Booleans)
varisRaining = true;
varisLoggedIn = false;
// 4. (Arrays)
varcolors = ["red", "green", "blue"];
// 5. object (Objects)
varplayer = {
name: "Ali",
score: 100

 };

📝 3️⃣ writing variables

variable definition JavaScript, Next :

1. No No $ _
2. No number
3. No can contain
4. variable names case-sensitive (name ≠ Name)
5. No ( for, if, let, class)

// ✅ variables :
letuserName = "Ahmed";
let_privateData = " ";
let$element = document.getElementById('id');
letfirstName = "Mohammed";
// ❌ variables :
// let 1stName = "Ahmed"; // number
// let user name = "Mohammed"; //
// let for = 5; // reserved word
// let let = "test"; // reserved word

🌐 4️⃣ (Scope)

variable:

// (Global Scope)
varglobalVar = " ";
// (Function Scope) - var
functiontestVar() {
varfunctionVar = " ";
console.log(functionVar); // ✅

 }
// console.log(functionVar); // ❌ False!
// (Block Scope) - let const
if (true) {
letblockVar = " ";
constBLOCK_CONST = " constant ";

 }
// console.log(blockVar); // ❌ False!