Web is responsive by default.
Increasing value of the responsive web design is not a innovative high-level approach. Thanks to fast propagation of wide spectrum of devices we'll back to the original web puropses and assumptions. For several years, we realized that using pixel units means rasterizing layouts.
Accessibility is the key.
Not only different devices but even different users preferences makes matter. Improving readibility and providing fast path to crucial content makes developer kings in the castle. But wait! Possibility to adjusting contrast and font parameters is a base. Our users wants more…
Modules likes a LEGO.
Components, modules, dependencies, injections, packages, generators, etc. … This terms widely comes into web world. Now, looks at your User Interface as a map of blocks with dependencies. How to simply loose coupling in JS/CSS/HTML layers?
Performance is everything.
Powerful features of front-end technologies and wide spread of end devices force from us to care about performance issues. Be friends with repaints&reflows allows to create performance confidently projects.