Implementing proof-of-work

Adding the proof-of-work mechanism to our homemade Javascript blockchain.

Proof-of-work will secure our blockchain against spammers and people trying to tamper with our blocks.

Blog post

Read my blog post if you want more information about this video.

The code used in this video is available on GitHub. It's in src/main-v2.js.

Feel free to fork it, improve it and open pull requests!