Variables
  • let variableName = value; //Mutable
  • const constantName = value; //Immutable
Data Types
  • String: “Hello”
  • Number: 50
  • Boolean: true or false
  • Array: let arr = [1,2,3];
  • Object: let obj = {key: ‘value’ };
Functions
  • String: “Hello”
  • Number: 50
  • Boolean: true or false
  • Array: let arr = [1,2,3];
  • Object: let obj = {key: ‘value’ };
Conditionals

if (condition) {

//Code

} else if (anotherCondition) {

//Code

} else {

//Code

}

Loops

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

// For…in loop for objects
for (let key in object) {
// Code
}

// For…of loop for arrays
for (let element of array) {
// Code
}

Arrays
  • let array = [1, 2, 3];
  • array.push(4); // Add to end
  • array.pop(); // Remove from end
  • array.shift(); // Remove from beginning
  • array.unshift(0); // Add to beginning
Objects

let person = {
name: ‘Harris’,
age: 20,
isStudent: true
};

DOM Manipulation
  • document.getElementById(‘elementId’);
  • document.querySelector(‘.className’);
  • element.addEventListener(‘click’, () => {
    // Code
    });
AJAX and Fetch
  • fetch(‘https://api.example.com/data’)
  • .then(response => response.json())
  • .then(data => console.log(data))
  • .catch(error => console.error(‘Error:’, error));
ES6+ Features
  • Destructuring: const { key } = object;
  • Spread Operator: const newArray = [...oldArray];
  • Template Literals: `Hello, ${name}!`
  • Promise: new Promise((resolve, reject) => { /* Code */ });
  • Async/Await: async function fetchData() { /* Code */ }