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.
elem.offsetLeft, elem.offsetTop, elem.offsetWidth, elem.offsetHeight, elem.offsetParent
I recently had several days of extremely frustrating experiences with service workers. Here are a few things I've since learned which would have made my life much easier but which isn't particularly obvious from most of the blog posts and videos I've seen.
I'll add to this list over time – suggested additions welcome in the comments or via twitter.com/rich_harris.
Chrome 51 has some pretty wild behaviour related to console.log in service workers. Canary doesn't, and it has a load of really good service worker related stuff in devtools.
| // It is important to declare your variables. | |
| (function() { | |
| var foo = 'Hello, world!'; | |
| print(foo); //=> Hello, world! | |
| })(); | |
| // Because if you don't, the become global variables. | |
| (function() { |
| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <title>Box Shadow</title> | |
| <style> | |
| .box { | |
| height: 150px; | |
| width: 300px; | |
| margin: 20px; |
| (function() { | |
| var CSSCriticalPath = function(w, d, opts) { | |
| var opt = opts || {}; | |
| var css = {}; | |
| var pushCSS = function(r) { | |
| if(!!css[r.selectorText] === false) css[r.selectorText] = {}; | |
| var styles = r.style.cssText.split(/;(?![A-Za-z0-9])/); | |
| for(var i = 0; i < styles.length; i++) { | |
| if(!!styles[i] === false) continue; | |
| var pair = styles[i].split(": "); |
I say "animated gif" but in reality I think it's irresponsible to be serving "real" GIF files to people now. You should be serving gfy's, gifv's, webm, mp4s, whatever. They're a fraction of the filesize making it easier for you to deliver high fidelity, full color animation very quickly, especially on bad mobile connections. (But I suppose if you're just doing this for small audiences (like bug reporting), then LICEcap is a good solution).
| /** | |
| * VH and VW units can cause issues on iOS devices: http://caniuse.com/#feat=viewport-units | |
| * | |
| * To overcome this, create media queries that target the width, height, and orientation of iOS devices. | |
| * It isn't optimal, but there is really no other way to solve the problem. In this example, I am fixing | |
| * the height of element `.foo` —which is a full width and height cover image. | |
| * | |
| * iOS Resolution Quick Reference: http://www.iosres.com/ | |
| */ | |
By: @BTroncone
Also check out my lesson @ngrx/store in 10 minutes on egghead.io!
Update: Non-middleware examples have been updated to ngrx/store v2. More coming soon!
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