Designers and Data Scientists have daily, weekly and monthly challenges. Now Developers can practice once each day, too!

1. DailyUI is free. It's 100 challenges delivered one day at a time via email. It's designed to make you a better designer.

2. Makeover Monday is free. It's a weekly data set and accompanying challenge shared by folks on Twitter. It's designed to make you a better storyteller with data.

3. storytelling with data is free. It's a monthly challenge shared among the similarly-titled book's community. It's designed to make you a better storyteller with data, too.

Fix a function! is free, too.

It is five new challenges each day. You can pick the language and the difficulty. It's designed to make you a more competent developer.

If you enjoy playing it, you can opt-in to daily email reminders. They are designed to help you form a habit of playing each day...of continuing to write code. That's the best way to learn.

Comments

[lionel-rowe]

There are some errors in a few of the exercises:

• arr.unshift(el) returns arr.length, not arr[0]
• arr.push(el) returns arr.length, not arr

You could avoid discrepancies between stated and actual output by evaling the user-submitted code in a sandboxed iframe and comparing the results. That way, you'd also no longer need to rely on exact text matches with the intended solution.