05 Performance

Perceived latency

When it comes to performance, there are important things and there is perceived latency.

Perceived latency

what users think affects performance and causes delays, what they see, while often having NOTHING to do with actual performance, is what really matters and makes them say your code works fast or slow.

1. Highest-voted StackOverflow answer to performance "how to" question is highest-voted mainly due to it covering perceived latency

2. Google article explaining perceived latency - explains how you can make your website simple, assure your users when they’re waiting and have good UI messages.

Tools

1. JS Perf

   1. JS Perf website

   2. Benchmark JS - JSPerf is based upon this

2. JSBen.ch

3. Closure compiler

4. Front-end dev tools:

   1. FireBug - for years a king of all front-end tools

   2. https://developer.mozilla.org/pl/docs/Tools/Performance

   3. https://developers.google.com/web/tools/chrome-devtools/rendering-tools/

5. JSLitmus for NPM

6. JSLitmus original

7. https://duzun.me/playground/js_speed{JS Speed] - simple and fast tool

APIs

1. https://developers.google.com/web/tools/chrome-devtools/console/console-reference#time

2. https://developers.google.com/web/tools/chrome-devtools/console/console-reference#profile

3. https://developer.mozilla.org/pl/docs/Web/API/Performance/now

Reading

1. High performance JS

2. 25 performance techniques in JS

3. Google pages about JS speed

4. every page under Best Practices

5. JQuery bind, live and delegate

6. http://www.w3schools.com/js/js_performance.asp

ℹ️	Switch statement compilation: 1. Wikipedia 2. Older OReilly article about efficient JS, the part about switch statement