JavaScript (Legacy)

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JavaScript is a scripting language, primarily used for creating dynamic websites and programming web servers. It's a very popular language, and supports a variety of programming paradigms.
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Our mentors are friendly, experienced JavaScript (Legacy) developers who will help teach you new techniques and tricks.
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923 Students

Join hundreds of students who have enjoyed learning and improving their skills by taking this track.
Track exercises

99 Exercises

Hundreds of hours have gone into making these exercises fun, useful, and challenging to help you enjoy learning.

About JavaScript (Legacy)

export function hello() {
  return 'Hello, World!';
};

ECMAScript is the standard that defines JavaScript, a programming language that allows web pages to be dynamic. It is an interpreted language, which means that it doesn't need to be compiled: instead the interpreter (such as a web browser) will parse the code and turn it into code that their machine can run - suitable for creating dynamic websites that can run on any browser* on any computer*!

JavaScript is not only for use in the browser. JavaScript runtimes, such as NodeJS and deno allow you to write, launch and serve requests on webservers. Other frameworks, such as Electron use JavaScript to write cross platform applications for Windows, Linux and Mac OS. Mobile app development is also a possibility, utilising react-native, ionic and various others, with expo now allowing to target Android, iOS and the web, all at once.

ECMAScript has grown to be one of the world’s most widely used general purpose programming languages. It is best known as the language embedded in web browsers but has also been widely adopted for server and embedded applications." — ECMA International Language Specification

Starting with the 6th edition (commonly known as ES2015 or ES6) in 2015, a new edition of the standard will be released each year. The 6th edition was a major update which brought many enhancements over ES5, including notably template strings, expressive arrow function syntax, and cleaner syntax for defining classes.

But because new syntax and features are coming to JavaScript each year, support for these changes is often incomplete in current browsers and the latest node. This doesn't mean we can't use it. Tools such as Babel offer transpilation for most features, allowing us to write as if it's the future.

Note: This track supports the latest ECMAScript syntax via Babel and the @babel/preset-env plugin, and new experimental features are enabled with each update of that plugin, matching the release of the specifications. It automatically adapts to your local node installation. This means you don't need to worry about what is and isn't supported.


* There is a small number of browsers that doesn't ship with a JavaScript runtime, or that has disabled JavaScript execution by default.

Join the JavaScript (Legacy) track

I learned so much by osmosis just from reading.

Exercism has been really wonderful for me. It was the first time that I ever contributed to an open source project (it's a nice feeling knowing that when people use Exercism I may have helped them in some way), how I learned JavaScript, and how I learned about testing and TDD. I learned so much by osmosis just from reading.

Fun. Challenging. Interesting

Community-sourced JavaScript (Legacy) exercises

These are a few of the 99 exercises on the JavaScript (Legacy) track. You can see all the exercises here.

Pangram
easy
algorithms
control flow conditionals
control flow loops
lists
maps
searching
strings
ISBN Verifier
medium
control flow conditionals
control flow loops
pattern recognition
regular expressions
Pascal's Triangle
medium
control flow conditionals
control flow loops
math
strings
text formatting
Roman Numerals
easy
control flow conditionals
control flow loops
pattern recognition
transforming
D&D Character
easy
classes
randomness
Change
hard
algorithms
performance
searching
Passionate. Knowledgeable. Creative.

Meet the JavaScript (Legacy) Track maintainers

The JavaScript (Legacy) Maintainers are the brains behind the JavaScript (Legacy) Track. They spend their spare time creating interesting and challenging exercises that we can all learn from. We are incredibly grateful for their hard work. Here are the bios of a few of the maintainers of this track.

Avatar of Tejas Bubane

Tejas Bubane My blog

Primarily a Ruby & Javascript coder, getting better at functional programming, emacs lover.
Avatar of Derk-Jan Karrenbeld

Derk-Jan Karrenbeld My website

All-round programmer, manager and owner of a Dutch software agency specializing in bespoke and tailored code.

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