Link to code and docs with permalinks where possible

When linking to a file or line of code on GitHub, SourceGraph, include the SHA to make it a permalink.

Why?

Source code changes over time, and line numbers may change. The file you're linking to may even be deleted! In order to ensure that your link works over time, always use permalinks where available.

Even if it's only a comment in JIRA or a quick slack message, it's still good practice to get in the habit of always copying permalinks. You never know when you might need to go back and reference a link you posted a while ago.

❌Bad:

https://github.com/facebook/react/blob/master/packages/react/src/ReactElement.js#L54

✅Good:

https://github.com/facebook/react/blob/ea155e2267b3/packages/react/src/ReactElement.js#L54

💡 Tip

Git SHAs can be shortened to just a few characters. So this:

https://github.com/facebook/react/blob/ea155e2267b3e4fd958d174f8f0e2b09b1c8ecf/packages/react/src/ReactElement.js

...can be condensed to:

https://github.com/facebook/react/blob/ea155e22/packages/react/src/ReactElement.js#L54

See more: https://stackoverflow.com/a/18134919/4396258