Based on data and features listed on Can I use, this app gives you the ability to select a number of front-end development features and get a percentage readout of the number of users worldwide that will see the features you choose.
A client-side, regular expression visualizer with a precise error indicator, should you have a syntax error in your expression. Also offers an option to embed the output anywhere, using an iframe.
A one-page website to help you grasp how to use the various useful but often complex nth-child based selector combinations.
“This page demonstrates the new HTML5 video element, its media API, and the media events. Play, pause, and seek in the entire video, change the volume, mute, change the playback rate (including going into negative values). See the effect on the video and on the underlying events and properties.”
This is probably a topic that all developers should be familiar with, and this might be a great place to start. It’s a comprehensive tutorial on cross-site scripting, a description of potential types of attacks, along with solutions for preventing them.
Meaning “Reasonable Standard for CSS Stylesheet Structure”, a work in progress to document some tips and techniques for writing Sass/CSS for very large projects.
“A project built by Andrew Hathaway with the aim to help fellow developers learn how to write their code in the nicest, most efficient and preferred way they can. To decide which code is the most preferred way, users can comment and vote against a fight for their favourite contender.” The site is divided into categories by programming languages, and there doesn’t seem to be a lot here yet, but you can help by adding to it and starting some “code fights”.
From the Sass master himself, Hugo Giraudel, “an opinionated styleguide for writing sane, maintainable and scalable Sass.” The guide has already been translated into 6 other languages.
“A community-curated list of flexbox issues and cross-browser workarounds for them. The goal is that if you’re building a website using flexbox and something isn’t working as you’d expect, you can find the solution here.” Definitely a must-bookmark for those starting to build new layouts with Flexbox.
Nothing too in-depth, just a simple set of reminders of stuff that all front-end developers should consider incorporating into their development process and workflow.
An in-depth, practical look at Flexbox, from Aussie-based developer Chris Wright. He’s also posted Using Flexbox Today, which tries to help you make the move to Flexbox in a logical, pragmatic manner.
A comprehensive site promoting and educating in the use of the popular BEM CSS methodology.
“Reporting incompatibilities between different Sass engines.”
A neat, logical, easy to use guide to get information on different HTML elements from the spec.
There’s lots of good info in Google’s Web Fundamentals documentation, but this one stands out for front-end devs in particular because of the importance of applying some good practices when animating UI elements.
“A painfully obsessive cheat sheet to favicon sizes/types.” Compiled from a number of different popular articles that discussed the ins and outs of favicons across desktop and mobile.
If you want your fill of CSS styleguides from some of the big players, Chris Coyier has put together a table with info and links to the various posts that were sort of trending for a couple of months last year. I’m sure he’ll continue to update this as others go public with their CSS methodologies and practices.
Finally, a native Mac or iOS app that is “an API Documentation Browser and Code Snippet Manager. Dash stores snippets of code and instantly searches offline documentation sets for 150+ APIs.” This one’s great for pretty much any kind of developer.