A JavaScript and WebAssembly program to easily play NSFe files (which contain Famicom and NES music) in the browser. GitHub repository
Synthesizing music from NSFe files instead of playing a compressed audio file allows you to have both small file size and quality.
Put the nsfplayer-mono-stereo.js Emscripten runtime and nsfplay-function.js in the head of your HTML document. From a click event, simply call nsfplay() with the name of your NSFe file and the number of the track you wish to play as arguments. Please view the source of this page for an example.