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Promises Workshop for JavaScript!

Learn to wield promises like a master to write clean asynchronous code

Uses ECMAScript 6 Promises

Dependency Status

Promise it won't hurt


Promises offer a very powerful abstraction for obtaining values asynchronously.
As JavaScript is a async-first language it is important to understand the options you have for handling asynchronicity.

You will learn the ins and outs of promises including error handling, value propagation, synchronous returns, and composition.

By the end of the workshop you will be comfortable using ES6 promises AND writing your own functions that leverage promises to provide clean abstractions and error handling.

Installation & Update

There are two ways to run the workshop:

1. NPM

Create a new directory to do your workshop work in. Let's call it "promise-shop". You will need to initialize npm in this repo.

$ mkdir promise-shop && cd promise-shop
$ npm init
$ npm install -g promise-it-wont-hurt@latest

Note: the workshop is being updated weekly. Please regularly rerun the above command to get the latest set of exercises.

2. Docker

Note for beginners: Do not do this if you do not have docker installed.

alias promise-it-wont-hurt='docker run -it -v $(pwd):/root oreng/promises-workshop'

promise-it-wont-hurt                        # show menu
promise-it-wont-hurt run mysolution.js      # run your solution
promise-it-wont-hurt verify mysolution.js   # verify your solution

The workshop stores your progress in .config so sudo rm -r .config will reset the workshop!

Usage Instructions

1. Selecting a problem to work on

Once the workshop is installed, run promise-it-wont-hurt to print a menu where you can select a problem to work on.

$ promise-it-wont-hurt

Problems are listed in rough order of difficulty. You are advised to complete them in order, as later problems will build on skills developed by solving previous problems.

2. Writing your solution

Once you have selected a problem, the workshop will remember which problem you are working on. Using your preferred editor, simply create a file to write your solution in.

3. Testing your solution

Use the workshop's run command to point the workshop at your solution file. Your solution will loaded and passed the problem input. This usually won't perform any validation, it will only show the program output.

$ promise-it-wont-hurt run mysolution.js

4. Verifying your solution

Your solution will be verified against the output of the 'official' solution. If all of the output matches, then you have successfully solved the problem!

$ promise-it-wont-hurt verify mysolution.js


Feedback and criticism is welcome, please log your troubles in issues.

Thanks rvagg

This tutorial was built using rvagg's workshopper framework.




A Workshopper module that teaches you to use promises in javascript






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