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paulirish /
Last active Dec 1, 2021
What forces layout/reflow. The comprehensive list.

What forces layout / reflow

All of the below properties or methods, when requested/called in JavaScript, will trigger the browser to synchronously calculate the style and layout*. This is also called reflow or layout thrashing, and is common performance bottleneck.

Generally, all APIs that synchronously provide layout metrics will trigger forced reflow / layout. Read on for additional cases and details.

Element APIs

Getting box metrics
  • elem.offsetLeft, elem.offsetTop, elem.offsetWidth, elem.offsetHeight, elem.offsetParent
basham /
Last active Nov 26, 2021
CSS Units Best Practices

CSS units

Recommendations of unit types per media type:

Media Recommended Occasional use Infrequent use Not recommended
Screen em, rem, % px ch, ex, vw, vh, vmin, vmax cm, mm, in, pt, pc
Print em, rem, % cm, mm, in, pt, pc ch, ex px, vw, vh, vmin, vmax

Relative units

Relative units

staltz /
Last active Nov 29, 2021
The introduction to Reactive Programming you've been missing

Lesson's learnt building the Guardian

Below is a collection of my favourite responses I gathered from Guardian engineers when asked the question: What have you learnt starting from scratch and building a mobile-first next generation web platform for the Guardian?

Daithi O Crualaoich

  • Work with great people.
  • Deploy like crazy. This means the team has to control the infrastructure as well as code.
  • Design is not a service. Designers have to sit in the team.
  • Infrastructure is intrinsically unreliable. Discard and replace is the robust strategy.
  • Use your CDN for HTML too.
  • Don't always do as you are told.