ES6+ Guide

Welcome to the ES6+ Guide! This section will cover the new features introduced in ES6 (ECMAScript 2015) and later versions, providing you with a comprehensive understanding of modern JavaScript.

Overview of ES6+ Features

• Let and Const: Introduced block-scoped variables, improving code readability and preventing unintentional variable reassignments.
• Arrow Functions: Simplified function expressions and provided a more concise syntax for writing functions.
• Template Literals: Allowed the creation of multi-line strings and the easy insertion of expressions and variables within strings.
• Promises and Async/Await: Improved asynchronous programming with a more intuitive and cleaner syntax.
• Modules: Introduced a way to organize and share code in a more structured manner.

Let and Const

Let and const were introduced to provide block-scoped variables, which means that the variables are limited to the block they are declared in, such as loops or if-statements.

for (let i = 0; i < 5; i++) {
  console.log(i);
}
// Output: 0, 1, 2, 3, 4

console.log(i); // Error: i is not defined

Use const to declare variables that should not be reassigned.

const PI = 3.14159;
// PI = 3.14; // Error: Assignment to constant variable.

Arrow Functions

Arrow functions provide a more concise syntax for writing functions and lexically bind the this value.

const multiply = (a, b) => a * b;
console.log(multiply(4, 5)); // Output: 20

Template Literals

Template literals allow you to create multi-line strings and insert expressions and variables within strings.

const name = "John";
const age = 30;

console.log(`My name is ${name} and I am ${age} years old.`);
// Output: My name is John and I am 30 years old.

Promises and Async/Await

Promises and async/await make asynchronous programming more intuitive and cleaner.

function fetchData() {
  return new Promise((resolve, reject) => {
    // Simulate fetching data with setTimeout
    setTimeout(() => {
      resolve("Data fetched successfully!");
    }, 2000);
  });
}

async function main() {
  try {
    const data = await fetchData();
    console.log(data); // Output: Data fetched successfully!
  } catch (error) {
    console.error(error);
  }
}

main();

Modules

Modules allow you to organize and share code in a more structured manner. You can create a module by exporting functions, objects, or variables, and then import them into other modules.

// myModule.js
export function add(a, b) {
  return a + b;
}

export function subtract(a, b) {
  return a - b;
}

// main.js
import { add, subtract } from './myModule.js';

console.log(add(4, 5)); // Output: 9
console.log(subtract(10, 3)); // Output: 7

For more information on ES6+ features and best practices, please visit our ES6+ Best Practices Guide.