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Integralist / Description.md
Last active April 25, 2020 16:20
This is how BBC News currently implements it's Image Enhancer for responsive images. Note: this is a completely rebuilt version of the code so the BBC's original source code doesn't actually look anything like the below example.

The BBC has a server-side image service which provides developers with multiple sized versions of any image they request. It works in a similar fashion to http://placehold.it/ but it also handles the image ratios returned (where as placehold.it doesn't).

The original BBC News process (and my re-working of the script) follows roughly these steps...

  • Create new instance of ImageEnhancer
  • Change any divs within the page (which have a class of delayed-image-load) into a transparent GIF using a Base64 encoded string.
    • We set the width & height HTML attributes of the image to the required size
    • We know what size the image needs to be because each div has custom data-attr set server-side to the size of the image
    • We then set a class of image-replace onto each newly created transparent image
  • We use a 250ms setTimeout to unblock the UI thread and which calls a function resizeImages which enhances the image-replace images so their source is now set to a URL whe
@rmurphey
rmurphey / gist:3086328
Created July 10, 2012 21:23
What's wrong with Netmag's "Optimize your JavaScript" post

What's wrong with Netmag's "Optimize your JavaScript" post

Update: The original post on Netmag has been updated since this was written.

I tweeted earlier that this should be retracted. Generally, these performance-related articles are essentially little more than linkbait -- there are perhaps an infinite number of things you should do to improve a page's performance before worrying about the purported perf hit of multiplication vs. division -- but this post went further than most in this genre: it offered patently inaccurate and misleading advice.

Here are a few examples, assembled by some people who actually know what they're talking about (largely Rick Waldron and Ben Alman, with some help from myself and several others from the place that shall be unnamed).

Things that are just plain wrong