Java-Script Cheat Sheet

Variables (let, const, var)

Used to store data values.

let name = "John";
const age = 25;
var city = "New York";

Data Types

Basic types: String, Number, Boolean, Array, Object.

let text = "Hello";
let number = 10;
let isTrue = true;

Operators

Used to perform operations on variables and values.

let sum = 5 + 3;
let isEqual = (5 === 5);

Functions

Reusable block of code.

function greet() {

   console.log("Hello World"); 

}

Arrow Function

Shorter syntax for writing functions.

const greet = () => {

   console.log("Hello"); 

};

If Statement

Executes code if a condition is true.

if (age > 18) {

   console.log("Adult"); 

}

For Loop

Repeats code a specific number of times.

for (let i = 0; i < 5; i++) {

   console.log(i); 

}

While Loop

Repeats code while a condition is true.

let i = 0;
while (i < 5) {

   console.log(i); 
   i++; 

}

Arrays

Stores multiple values in one variable.

let fruits = ["Apple", "Banana", "Orange"];

Objects

Stores data in key-value pairs.

let person = {

   name: "John", 
   age: 25 

};

DOM Selection

Selects HTML elements.

document.getElementById("id");
document.querySelector(".class");

Event Listener

Runs code when an event occurs.

button.addEventListener("click", function() {

   alert("Button clicked!"); 

});

Console

Outputs messages for debugging.

console.log("Hello World");

Return Statement

Sends a value back from a function.

function add(a, b) {

   return a + b; 

}

Conditional (Ternary) Operator

Short-hand for if...else statements.

let result = (age >= 18) ? "Adult" : "Minor";