TinyWFL - Tiny Web Font Loader
TinyWFL is a minimal web font loader which uses a similar approach to Google's and Typekit's webfontloader to help you avoid the FOUT (flash of unstyled text), except it does a lot less so it can stay tiny - is 95% smaller, at just 852 bytes.
TinyWFL will set CSS styles on your <html> tag when your fonts have loaded, and call an optional callback function if you want to know about it in JavaScript.
Read the documentation and grab the code from github.