Using Angular markup like {{hash}} in a srcset attribute doesn't work right: The browser will fetch from the URL with the literal text {{hash}} until Angular replaces the expression inside {{hash}}. The ngSrcset directive solves this problem.

The buggy way to write it:

<img srcset="http://www.gravatar.com/avatar/{{hash}} 2x" alt="Description"/>

The correct way to write it:

<img ng-srcset="http://www.gravatar.com/avatar/{{hash}} 2x" alt="Description" />