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Ecosystems

Economic Systems

Business Leaders

Non-Technical

Innovators

IT Professional

Technical

Developers

Architects

Very Technical

Researchers

Integrations

Connectors

Interoperability

Perspectives

Insights

Synthesis

Solutions

Ecosystems

Economic Systems

Business Leaders

Non-Technical

Innovators

IT Professional

Technical

Developers

Architects

Very Technical

Researchers

Integrations

Connectors

Interoperability

Perspectives

Insights

Synthesis

ES6+ Features

Last Updated: Apr 13, 2025

Let and Const (Block-Scoped Variables)

ES6 introduced let and const to replace var.

  • let allows reassigning values but is block-scoped.

  • const prevents reassignment and is also block-scoped.

let name = "Alice";
name = "Bob"; // Allowed
  
const age = 30;
age = 31; // Error: Assignment to constant variable

Block Scope Example

if (true) {
  let x = 10;
  console.log(x); // 10
}
console.log(x); // Error: x is not defined

Template Literals (String Interpolation)

Template literals use backticks (`) and allow embedding expressions using ${}.

let user = "Alice";
console.log(`Hello, ${user}!`); // Outputs: Hello, Alice!

Multiline strings are also possible:

let message = `This is
a multiline
string.`;
console.log(message);

Arrow Functions

Arrow functions provide a concise syntax for defining functions.

const add = (a, b) => a + b;
console.log(add(5, 3)); // Outputs: 8

If there’s only one parameter, parentheses can be omitted:

const greet = name => `Hello, ${name}`;
console.log(greet("Alice"));

Arrow functions do not have their own this binding, which makes them useful in certain contexts like callbacks.

Destructuring Assignment

Destructuring simplifies extracting values from arrays and objects.

Array Destructuring

let colors = ["red", "green", "blue"];
let [first, second] = colors;
console.log(first, second); // Outputs: red green

Skipping elements:

let [, , third] = colors;
console.log(third); // Outputs: blue

Object Destructuring

let person = { name: "Alice", age: 25 };
let { name, age } = person;
console.log(name, age); // Outputs: Alice 25

Renaming variables:

let { name: fullName } = person;
console.log(fullName); // Outputs: Alice

Rest Operator

Used in function parameters to collect multiple arguments.

function sum(...numbers) {
    return numbers.reduce((acc, num) => acc + num, 0);
  }
console.log(sum(1, 2, 3, 4)); // Outputs: 10

Default Parameters

Functions can have default values for parameters.

function greet(name = "Guest") {
  console.log(`Hello, ${name}`);
}
greet(); // Outputs: Hello, Guest
greet("Alice"); // Outputs: Hello, Alice

Modules (Import/Export)

ES6 introduced modules for better code organization.

Exporting a Module

// math.js
export function add(a, b) {
     return a + b;
}
  
export const PI = 3.14;

Importing a Module

// main.js
import { add, PI } from "./math.js";
console.log(add(2, 3)); // Outputs: 5
console.log(PI); // Outputs: 3.14

For default exports:

// message.js
export default function message() {
  console.log("This is a default export");
}
  
// main.js
import msg from "./message.js";
msg();

Promises (Asynchronous JavaScript)

Promises simplify handling asynchronous operations.

let fetchData = new Promise((resolve, reject) => {
  setTimeout(() => resolve("Data loaded"), 2000);
});
  
fetchData.then(result => console.log(result)); // Outputs after 2 seconds: Data loaded

Handling errors:

fetchData
  .then(result => console.log(result))
  .catch(error => console.log(error));

Async/Await

async functions work with await to simplify promises.

async function fetchData() {
  return "Data received";
}
  
fetchData().then(data => console.log(data));

Using await inside an async function:

async function fetchUser() {
  let response = await fetch("https://jsonplaceholder.typicode.com/users/1");
  let user = await response.json();
  console.log(user);
}
  
fetchUser();

Conclusion

ES6+ features improve JavaScript's efficiency, readability, and maintainability. The next section will explore asynchronous JavaScript, covering callbacks, promises, and async/await in detail.

Previous

es6-features

Next

introduction

Elements

ES6+ Features

Last Updated: Apr 13, 2025

Let and Const (Block-Scoped Variables)

ES6 introduced let and const to replace var.

  • let allows reassigning values but is block-scoped.

  • const prevents reassignment and is also block-scoped.

let name = "Alice";
name = "Bob"; // Allowed
  
const age = 30;
age = 31; // Error: Assignment to constant variable

Block Scope Example

if (true) {
  let x = 10;
  console.log(x); // 10
}
console.log(x); // Error: x is not defined

Template Literals (String Interpolation)

Template literals use backticks (`) and allow embedding expressions using ${}.

let user = "Alice";
console.log(`Hello, ${user}!`); // Outputs: Hello, Alice!

Multiline strings are also possible:

let message = `This is
a multiline
string.`;
console.log(message);

Arrow Functions

Arrow functions provide a concise syntax for defining functions.

const add = (a, b) => a + b;
console.log(add(5, 3)); // Outputs: 8

If there’s only one parameter, parentheses can be omitted:

const greet = name => `Hello, ${name}`;
console.log(greet("Alice"));

Arrow functions do not have their own this binding, which makes them useful in certain contexts like callbacks.

Destructuring Assignment

Destructuring simplifies extracting values from arrays and objects.

Array Destructuring

let colors = ["red", "green", "blue"];
let [first, second] = colors;
console.log(first, second); // Outputs: red green

Skipping elements:

let [, , third] = colors;
console.log(third); // Outputs: blue

Object Destructuring

let person = { name: "Alice", age: 25 };
let { name, age } = person;
console.log(name, age); // Outputs: Alice 25

Renaming variables:

let { name: fullName } = person;
console.log(fullName); // Outputs: Alice

Rest Operator

Used in function parameters to collect multiple arguments.

function sum(...numbers) {
    return numbers.reduce((acc, num) => acc + num, 0);
  }
console.log(sum(1, 2, 3, 4)); // Outputs: 10

Default Parameters

Functions can have default values for parameters.

function greet(name = "Guest") {
  console.log(`Hello, ${name}`);
}
greet(); // Outputs: Hello, Guest
greet("Alice"); // Outputs: Hello, Alice

Modules (Import/Export)

ES6 introduced modules for better code organization.

Exporting a Module

// math.js
export function add(a, b) {
     return a + b;
}
  
export const PI = 3.14;

Importing a Module

// main.js
import { add, PI } from "./math.js";
console.log(add(2, 3)); // Outputs: 5
console.log(PI); // Outputs: 3.14

For default exports:

// message.js
export default function message() {
  console.log("This is a default export");
}
  
// main.js
import msg from "./message.js";
msg();

Promises (Asynchronous JavaScript)

Promises simplify handling asynchronous operations.

let fetchData = new Promise((resolve, reject) => {
  setTimeout(() => resolve("Data loaded"), 2000);
});
  
fetchData.then(result => console.log(result)); // Outputs after 2 seconds: Data loaded

Handling errors:

fetchData
  .then(result => console.log(result))
  .catch(error => console.log(error));

Async/Await

async functions work with await to simplify promises.

async function fetchData() {
  return "Data received";
}
  
fetchData().then(data => console.log(data));

Using await inside an async function:

async function fetchUser() {
  let response = await fetch("https://jsonplaceholder.typicode.com/users/1");
  let user = await response.json();
  console.log(user);
}
  
fetchUser();

Conclusion

ES6+ features improve JavaScript's efficiency, readability, and maintainability. The next section will explore asynchronous JavaScript, covering callbacks, promises, and async/await in detail.

Previous

es6-features

Next

introduction

ES6+ Features

Last Updated: Apr 13, 2025

Let and Const (Block-Scoped Variables)

ES6 introduced let and const to replace var.

  • let allows reassigning values but is block-scoped.

  • const prevents reassignment and is also block-scoped.

let name = "Alice";
name = "Bob"; // Allowed
  
const age = 30;
age = 31; // Error: Assignment to constant variable

Block Scope Example

if (true) {
  let x = 10;
  console.log(x); // 10
}
console.log(x); // Error: x is not defined

Template Literals (String Interpolation)

Template literals use backticks (`) and allow embedding expressions using ${}.

let user = "Alice";
console.log(`Hello, ${user}!`); // Outputs: Hello, Alice!

Multiline strings are also possible:

let message = `This is
a multiline
string.`;
console.log(message);

Arrow Functions

Arrow functions provide a concise syntax for defining functions.

const add = (a, b) => a + b;
console.log(add(5, 3)); // Outputs: 8

If there’s only one parameter, parentheses can be omitted:

const greet = name => `Hello, ${name}`;
console.log(greet("Alice"));

Arrow functions do not have their own this binding, which makes them useful in certain contexts like callbacks.

Destructuring Assignment

Destructuring simplifies extracting values from arrays and objects.

Array Destructuring

let colors = ["red", "green", "blue"];
let [first, second] = colors;
console.log(first, second); // Outputs: red green

Skipping elements:

let [, , third] = colors;
console.log(third); // Outputs: blue

Object Destructuring

let person = { name: "Alice", age: 25 };
let { name, age } = person;
console.log(name, age); // Outputs: Alice 25

Renaming variables:

let { name: fullName } = person;
console.log(fullName); // Outputs: Alice

Rest Operator

Used in function parameters to collect multiple arguments.

function sum(...numbers) {
    return numbers.reduce((acc, num) => acc + num, 0);
  }
console.log(sum(1, 2, 3, 4)); // Outputs: 10

Default Parameters

Functions can have default values for parameters.

function greet(name = "Guest") {
  console.log(`Hello, ${name}`);
}
greet(); // Outputs: Hello, Guest
greet("Alice"); // Outputs: Hello, Alice

Modules (Import/Export)

ES6 introduced modules for better code organization.

Exporting a Module

// math.js
export function add(a, b) {
     return a + b;
}
  
export const PI = 3.14;

Importing a Module

// main.js
import { add, PI } from "./math.js";
console.log(add(2, 3)); // Outputs: 5
console.log(PI); // Outputs: 3.14

For default exports:

// message.js
export default function message() {
  console.log("This is a default export");
}
  
// main.js
import msg from "./message.js";
msg();

Promises (Asynchronous JavaScript)

Promises simplify handling asynchronous operations.

let fetchData = new Promise((resolve, reject) => {
  setTimeout(() => resolve("Data loaded"), 2000);
});
  
fetchData.then(result => console.log(result)); // Outputs after 2 seconds: Data loaded

Handling errors:

fetchData
  .then(result => console.log(result))
  .catch(error => console.log(error));

Async/Await

async functions work with await to simplify promises.

async function fetchData() {
  return "Data received";
}
  
fetchData().then(data => console.log(data));

Using await inside an async function:

async function fetchUser() {
  let response = await fetch("https://jsonplaceholder.typicode.com/users/1");
  let user = await response.json();
  console.log(user);
}
  
fetchUser();

Conclusion

ES6+ features improve JavaScript's efficiency, readability, and maintainability. The next section will explore asynchronous JavaScript, covering callbacks, promises, and async/await in detail.

Previous

es6-features

Next

introduction
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Careers

Contact Us

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Ecosystem Partners

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Legal Hub

User Privacy Statement

Security Posture

Terms & Conditions

FOLLOW US

X (Twitter)

LinkedIn

Copyright ©2025. Open Ecosystems

ECOSYSTEMS

Teladoc + Lyft

See All

RESOURCES

Case Studies

Books

Research Reports

Blogs

ORGANIZATION

Services

Careers

Contact Us

Press

PARTNERS

Ecosystem Partners

People

LEGAL

Legal Hub

User Privacy Statement

Security Posture

Terms & Conditions

FOLLOW US

X (Twitter)

LinkedIn

Copyright ©2025. Open Ecosystems