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A javascript library that sets out to do one simple job: draw and animate the most perfect and playful text underline


The project is currently under development.

If you have 8 minutes and want to know what is the story behind creating underline.js, you can hear all about it in this NY Tech Meetup presentation video


Underline.js has following features:

  1. It doesn't have ghost pixels. It is not just pixel perfect, but also pixel perfect on half pixel level for retina display pixel-perfect
  2. It has an optimized thin stroke-width. It is always 1/6 of width of the period mark. optimal-stroke-width
  3. It sits on the optimal Y position between the baseline and descender line, that optimal Y positon is the golden ratio point. golden-ratio
  4. It has holes around descenders. Completely respect the type's shape. If you ask, the size of the holes are also optimized to the perfection. descender-holes

CSS4 Proposal to W3C

Underline.js is not designed to be the most useful javascript library. It is more exploratory, and it is trying to push the boundary of web typography. I want to propose these new css rules to W3C for css4 edition:

text-underline-color: #000000;
// auto means the same color as the text color, or hex value

text-underline-position: auto;
// could be ratio or px or auto

text-underline-skip: true;
// true to set holes around descenders, false to turn it off

text-underline-width: auto;
// could be auto or px or ratio

text-underline-animation: true
// true or false, this one is only for underline.js


Marcin Wichary's article on crafting's underline

Mentions (thank you!)

Tweets article

codrops collective Note: underline.js doesn't have dependency on jquery Parsons Alumni news us8



Pushing the boundary of browser typography rendering!



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