FitText makes font sizing flexible. Use this library on your fluid or responsive layout to achieve scalable headlines that fill the width of a parent element.

Now supporting UMD, and of course no jQuery requirement.

FitText-UMD supports UMD and may be loaded as a module. In this example, "responsive_headline" is the id of an element that we want the text to dynamically size to.

    var fitText = require("FitText-UMD");
    fitText( document.getElementById("responsive_headline") );

FitText-UMD may optionally be loaded globally in the HEAD, making it accessible via the window object.

npm install
npm run example

Open https://localhost:8080 in the browser.

The default setting works pretty well, but when it doesn't FitText has one setting you can adjust. If your text resizes poorly or is resizing all hurdy gurdy, you'll want to turn tweak up/down the compressor. It works a little like a guitar amp.

fitText( document.getElementById("responsive_headline"), 1.2 ); // turn the compressor up (font will shrink a bit more aggressively)
fitText( document.getElementById("responsive_headline"), 0.8 ); // turn the compressor down (font will shrink less aggressively)

This will hopefully give you a level of "control" that might not be pixel perfect, but scales smoothly & nicely.

With the removal of jQuery, element resize events are no longer available. jQuery uses an inefficient polling method to detect element resizing so a better solution is needed anyway. One potential candidate:
https://github.com/marcj/css-element-queries

Thanks to adactio for eliminating the need for jQuery: https://github.com/adactio/FitText.js
Thanks to Trent, Dave and Reagan for original FitText.js: https://github.com/davatron5000/FitText.js
https://fittextjs.com/