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index.md 2.3KB
index.md 2.3KB
title: Everyone has JavaScript, right?
url: http://kryogenix.org/code/browser/everyonehasjs.html
hash_url: cbd31f4a6e
- Your user requests your web app
- Has the page loaded yet?
- “All your users are non-JS while they're downloading your JS” — Jake Archibald
- Did the HTTP request for the JavaScript succeed?
- If they're on a train and their net connection goes away before your JavaScript loads, then there's no JavaScript.
- Did the HTTP request for the JavaScript complete?
- How many times have you had a mobile browser hang forever loading a page and then load it instantly when you refresh?
- Does the corporate firewall block JavaScript?
- Because loads of them still do.
- Does their ISP or mobile operator interfere with downloaded JavaScript?
- Sky accidentally block jQuery, Comcast insert ads into your script, and if you've never experienced this before, drive to an airport and use their wifi.
- Have they switched off JavaScript?
- People still do.
- Do they have addons or plugins installed which inject script or alter the DOM in ways you didn't anticipate?
- There are thousands of browser extensions. Are you sure none interfere with your JS?
- Is the CDN up?
- CDNs are good at staying up (that’s what being a CDN is) but a minute downtime a month will still hit users who browse in that minute.
- Does their browser support the JavaScript you’ve written?
- Check Can I Use for browser usage figures.
Is all the above true?
Then yes, your JavaScript works.
Probably.
Progressive enhancement. Because sometimes your JavaScript just won’t work.
Be prepared.