freeCodeCamp.org's open-source codebase and curriculum

freeCodeCamp.org is a friendly community where you can learn to code for free. It is run by a donor-supported 501(c)(3) nonprofit to help millions of busy adults transition into tech. Our community has already helped more than 10,000 people get their first developer job.

Our full-stack web development and machine learning curriculum is completely free and self-paced. We have thousands of interactive coding challenges to help you expand your skills.

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Certifications

freeCodeCamp.org offers several free developer certifications. Each of these certifications involves building 5 required web app projects, along with hundreds of optional coding challenges to help you prepare for those projects. We estimate that each certification will take a beginner programmer around 300 hours to earn.

Each of these 50…

You Don't Know JS Yet (book series) - 2nd Edition

This is a series of books diving deep into the core mechanisms of the JavaScript language. This is the second edition of the book series:

To read more about the motivations and perspective behind this book series, check out the Preface.

If you're looking for the previous first edition books, they can be found here.

Premier Sponsor

This edition of the YDKJS book series is exclusively sponsored by Frontend Masters.

Frontend Masters is the gold standard for top-of-the-line expert training material in frontend-oriented software development. With over 150 courses on all things frontend, this should be your first and only stop for quality video training on HTML, CSS, JS, and related technologies.

I teach all my workshops exclusively through Frontend Masters. If you like this book content, please check out my video training courses.

I want…

JavaScript Algorithms and Data Structures

This repository contains JavaScript based examples of many popular algorithms and data structures.

Each algorithm and data structure has its own separate README with related explanations and links for further reading (including ones to YouTube videos).

Read this in other languages: 简体中文 繁體中文 한국어 日本語, Polski, Français, Español, Português, Русский, Türk, Italiana, Bahasa Indonesia, Українська, Arabic, Deutsch

☝ Note that this project is meant to be used for learning and researching purposes only, and it is not meant to be used for production.

Data Structures

A data structure is a particular way of organizing and storing data in a computer so that it can be accessed and modified efficiently. More precisely, a data structure is a collection of data values, the relationships among them, and the functions or operations that can…

30 seconds of code

Short JavaScript code snippets for all your development needs

• Visit our website to view our snippet collection.
• Use the Search page to find snippets that suit your needs. You can search by name, tag, language or using a snippet's description. Just start typing a term and see what comes up.
• Browse the JavaScript Snippet List to see all the snippets in this project or click individual tags at the top of the same page to narrow down your search to a specific tag.
• Click on each snippet card to view the whole snippet, including code, explanation and examples.
• You can use the button on the right side of a snippet card to copy the code to clipboard.
• If you like the project, give it a star. It means a lot to the people maintaining it.

Want to contribute?

• If you want to help us improve, take…

Node.js Best Practices

Follow us on Twitter! @nodepractices

Read in a different language: , , , , ,

Built and maintained by our Steering Committee and Collaborators

Latest Best Practices and News

• Basque translation by father and daughter!: wow even our Basque readers can read in their mother-tongue language! Courtesy of Ane Diaz de Tuesta and her father Joxefe Diaz de Tuesta 💜. Great family work

• 🇯🇵 Japanese translation: Our guide is now also translated to Japanese! Courtesy of the amazing YukiOta and Yuta Azumi

• 🎊 60,000 stars!: Our repo was starred and trusted by 60,100 developers. We're speechless

Welcome! 3 Things You Ought To Know First

1. You are reading dozens of the best Node.js articles - this repository is a summary and curation of the top-ranked content…

  Front-End Checklist  

The Front-End Checklist is an exhaustive list of all elements you need to have / to test before launching your website / HTML page to production.

  How To Use • Contributing • Website • Product Hunt

Other Checklists:
  🎮 Front-End Performance Checklist • 💎 Front-End Design Checklist

It is based on Front-End developers' years of experience, with the additions coming from some other open-source checklists.

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How to use?

All items in the Front-End Checklist are required for the majority of the projects, but some elements can be omitted or are not essential (in the case of an administration web app, you may not need RSS feed for example). We choose to use 3 levels of flexibility:

• means that the item is recommended but can be omitted in some particular situations.
• means that the item…

clean-code-javascript

Table of Contents

Introduction

Software engineering principles, from Robert C. Martin's book Clean Code adapted for JavaScript. This is not a style guide. It's a guide to producing readable, reusable, and refactorable software in JavaScript.

Not every principle herein has to be strictly followed, and even fewer will be universally agreed upon. These are guidelines and nothing more, but they are ones codified over many years of collective experience by the authors of Clean Code.

Our craft of software engineering is just a bit over 50 years old, and we are still learning a lot. When software architecture is as old as architecture itself, maybe then we will have harder rules to follow. For now, let these guidelines serve as a touchstone by which to assess the quality of the JavaScript…

33 Concepts Every JavaScript Developer Should Know

Introduction

This repository was created with the intention of helping developers master their concepts in JavaScript. It is not a requirement, but a guide for future studies. It is based on an article written by Stephen Curtis and you can read it here.

🚀 Considered by GitHub as one of the top open source projects of 2018!

Community

Feel free to submit a PR adding a link to your own recaps or reviews. If you want to translate the repo into your native language, please feel free to do so.

All the translations for this repo will be listed below:

• Albanian — Eldrin Ereqi
• Arabic — Amr Elsekilly
• Chinese — Re Tian
• Portuguese-BR — Tiago Boeing
• Korean — Suin Lee
• Spanish — Adonis Mendoza
• Turkish — İlker Demir
• Russian — Mihail Gumennii
• Tiếng Việt — Nguyễn Trần Chung
• Polish — Dawid Lipinski

Leaflet is the leading open-source JavaScript library for mobile-friendly interactive maps Weighing just about 39 KB of gzipped JS plus 4 KB of gzipped CSS code, it has all the mapping features most developers ever need.

Leaflet is designed with simplicity, performance and usability in mind It works efficiently across all major desktop and mobile platforms out of the box taking advantage of HTML5 and CSS3 on modern browsers while being accessible on older ones too. It can be extended with a huge amount of plugins, has a beautiful, easy to use and well-documented API and a simple, readable source code that is a joy to contribute to.

For more info, docs and tutorials, check out the official website.
For Leaflet downloads (including the built master version), check out the download page.

We're happy to meet new contributors If you want to get involved with…

Front End Interview Handbook

Credits: Illustration by @yangheng

Read on the website

Black Lives Matter. Support the Equal Justice Initiative

What is this?

Unlike typical software engineer job interviews, front-end job interviews have less emphasis on algorithms and have more questions on intricate knowledge and expertise about the domain — HTML, CSS, JavaScript, just to name a few areas.

While there are some existing resources to help front end developers in preparing for interviews, they aren't as abundant as materials for a software engineer interview. Among the existing resources, probably the most helpful question bank would be Front-end Developer Interview Questions. Unfortunately, I couldn't find many complete and satisfactory answers to these questions online, hence here is my attempt at answering them. Being an open source repository, the project can live on with the support of the community as the state of web evolves.

Why do I want this?

date-fns provides the most comprehensive, yet simple and consistent toolset
for manipulating JavaScript dates in a browser & Node.js

It's like Lodash for dates

• It has 200+ functions for all occasions.
• Modular: Pick what you need. Works with webpack, Browserify, or Rollup and also supports tree-shaking.
• Native dates: Uses existing native type. It doesn't extend core objects for safety's sake.
• Immutable & Pure: Built using pure functions and always returns a new date instance.
• TypeScript & Flow: Supports both Flow and TypeScript
• I18n: Dozens of locales. Include only what you need.
• and many more benefits

import { compareAsc, format } from 'date-fns'
format(new Date(2014, 1, 11), 'yyyy-MM-dd')
//=> '2014-02-11'

const dates = [
  new Date(1995, 6, 2),
  new Date(1987

中文版 | 日本語版 | 한국어 | Русский | Português

Project Guidelines ·

While developing a new project is like rolling on a green field for you, maintaining it is a potential dark twisted nightmare for someone else Here's a list of guidelines we've found, written and gathered that (we think) works really well with most JavaScript projects here at elsewhen If you want to share a best practice, or think one of these guidelines should be removed, feel free to share it with us.

1. Git

1.1 Some Git rules

There are a set of rules to keep in mind:

• Perform work in a feature branch.

  Why:

  …

Modern JavaScript Cheatsheet

Image Credits: Ahmad Awais ⚡️

If you like this content, you can ping me or follow me on Twitter 👍

Introduction

Motivation

This document is a cheatsheet for JavaScript you will frequently encounter in modern projects and most contemporary sample code.

This guide is not intended to teach you JavaScript from the ground up, but to help developers with basic knowledge who may struggle to get familiar with modern codebases (or let's say to learn React for instance) because of the JavaScript concepts used.

Besides, I will sometimes provide personal tips that may be debatable but will take care to mention that it's a personal recommendation when I do so.

Note: Most of the concepts introduced here are coming from a JavaScript language update (ES2015, often called ES6). You can find new features added by this update here; it's very well done.

Complementary Resources

When you…

Ramda

A practical functional library for JavaScript programmers.

Why Ramda?

There are already several excellent libraries with a functional flavor. Typically, they are meant to be general-purpose toolkits, suitable for working in multiple paradigms. Ramda has a more focused goal. We wanted a library designed specifically for a functional programming style, one that makes it easy to create functional pipelines, one that never mutates user data.

What's Different?

The primary distinguishing features of Ramda are:

• Ramda emphasizes a purer functional style. Immutability and side-effect free functions are at the heart of its design philosophy. This can help you get the job done with simple elegant code.

• Ramda functions are automatically curried. This allows you to easily build up new functions from old ones simply by not supplying the final parameters.

• The parameters to Ramda functions are arranged to make it convenient for currying. The data to be operated on is…

You (Might) Don't Need jQuery

Frontend environments evolve rapidly nowadays and modern browsers have already implemented a great deal of DOM/BOM APIs which are good enough for production use. We don't have to learn jQuery from scratch for DOM manipulation or event handling. In the meantime, thanks to the spread of frontend libraries such as React, Angular and Vue, manipulating the DOM directly becomes anti-pattern, so that jQuery usage has never been less important. This project summarizes most of the alternatives in native Javascript implementation to jQuery methods, with IE 10+ support.

ℹ️ Notice:

1. jQuery is still a great library and has many valid use cases. Don’t migrate away if you don’t want to!
2. The alternatives are not completely equivalent in all scenarios, and it is recommended that you test it before using it.

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JavaScript Stack from Scratch

Welcome to my modern JavaScript stack tutorial: JavaScript Stack from Scratch.

🎉This is the V2 of the tutorial, major changes happened since the 2016 release. Check the Change Log!

This is a straight-to-the-point guide to assembling a JavaScript stack. It requires some general programming knowledge, and JavaScript basics. It focuses on wiring tools together and giving you the simplest possible example for each tool. You can see this tutorial as a way to write your own boilerplate from scratch. Since the goal of this tutorial is to assemble various tools, I do not go into details about how these tools work individually. Refer to their documentation or find other tutorials if you want to acquire deeper knowledge in them.

You don't need to use this entire stack if you build a simple web page with a few JS interactions of course (a…