Mozilla created in the last years many JavaScript libraries that can help you on your dev life and maybe you don't know them.
https://github.com/mozilla/localforage
localforage.setItem(key, value, function() {
console.log('Saved: ' + value);
});
localforage.getItem(key, function(err, readValue) {
console.log('Read: ', readValue);
});
https://github.com/mozilla/fxpay
https://github.com/mozilla/nunjucks
{% extends "base.html" %}
{% asyncAll item in items %}
<li>{{ item.id | lookup }}</li>
{% endall %}
{% block content %}
{{ page.content }}
{% endblock %}
https://github.com/mozilla/metrics-graphics
http://metricsgraphicsjs.org/examples.htm
https://github.com/mozilla/pdf.js
https://aframe.io/
<a-scene>
</a-scene>
http://sweetjs.org/
https://github.com/mozilla/vtt.js
http://popcornjs.org/
http://l20n.org/
https://togetherjs.com/
https://github.com/mozilla-b2g/exif-parser
http://mozilla.github.io/shumway/
http://emscripten.org/
https://github.com/kripken/emscripten/wiki/Porting-Examples-and-Demos
https://platform-status.mozilla.org/
https://github.com/webcompat/css-fixme
https://github.com/MozillaSecurity/FuzzManager
https://github.com/MozillaSecurity/funfuzz
https://github.com/MozillaSecurity/funfuzz/tree/master/dom
https://github.com/MozillaSecurity/funfuzz/tree/master/js/jsfunfuzz