This library makes it easy to incorporate sheet music into your websites. You can also turn visible ABC text into sheet music on websites that you don't own using a greasemonkey script, or change your own website that contains ABC text with no other changes than the addition of one javascript file. You can also generate MIDI files or play them directly in your browser.
Full documentation is here: abcjs documentation
If you aren't using the same browser and machine that I use, you can thank BrowserStack for their support of this open-source project.