Few articles and tutorials you may have a look at.

CSS good practices

SMACSS
A flexible guide to write modular and scalable CSS.
An introduction to OOCSS
Great article introducing the Object Oriented CSS principle, how does it work and why it could be helpful for your projects.
BEM syntax
Short summary of what the BEM naming methodology is.
You may also have a look at this developed post.

JS development

The intro to Reactive Programming you've been missing
Really great introduction to (Functional) Reactive Programming and to Rx.js.
The mostly adequate guide to functional programming
To dig into functional programming from 0 to the infinity − and beyond.
Functional JavaScript
Excellent book introduction concepts of functional programming with JavaScript, presented upon Underscore.js
Developing Backbone.js applications
An exhaustive guide to introduce you all the basics you'll need to develop with Backbone.js
From jQuery to Backbone.js
A jQuery code turns into Backbone.js logic, step by step.

Front-end performance

How to lose weight (in the browser)
The definitive front-end performance guide for developers.
Front-end performance by CSSWizardry
Few thoughts from Harry Roberts about performance for web designers and front-end developers.
High Performance Networking in Chrome
An interesting article about Google Chrome performance. Little bit technical but worth reading.