A few conversations have circled around user-side structural profiling. For context, see React PR #7549: Show React events in the timeline when ReactPerf is active
One particular concern is the measurement overhead. This gist has a benchmarking script (measure.js) for evaluating overhead and initial results.
Runs about 0.65µs per mark() call. Naturally, that's ~= an overhead of 1ms for 1500 mark()s.
| { | |
| "version": "0.1.0", | |
| "command": "cmd", | |
| "isShellCommand": true, | |
| "showOutput": "silent", | |
| "args": [ | |
| "/c" | |
| ], | |
| "tasks": [ | |
| { |
| <filetype binary="false" description="Logstash Config" name="Logstash Config"> | |
| <highlighting> | |
| <options> | |
| <option name="LINE_COMMENT" value="#" /> | |
| <option name="COMMENT_START" value="" /> | |
| <option name="COMMENT_END" value="" /> | |
| <option name="HEX_PREFIX" value="" /> | |
| <option name="NUM_POSTFIXES" value="" /> | |
| <option name="HAS_BRACES" value="true" /> | |
| <option name="HAS_BRACKETS" value="true" /> |
Greetings and salutations, NSHipsters!
As the year winds down, it's a tradition here at NSHipster to ask you, dear readers, to offer up your favorite tricks and tips from the past year as gifts to your fellow hipsters. With iOS 9, El Capitan, brand new watch- and tvOS's, and the open-sourcing of some minor Apple-related tech, there's bound to be lots to share.
Submit your favorite piece of Swift or @objc trivia, helpful hints, unexpected discoveries, useful workarounds, useless fascinations, or anything else you found cool this year. Just comment below!
If you need inspiration, try [the list from last year][2015], or [from the year before][2014], or [from the year before that][2013].
| // Swift Standard Librray - String | |
| // Keith Harrison http://useyourloaf.com | |
| // Import Foundation if you want to bridge to NSString | |
| import Foundation | |
| // ==== | |
| // Initializing a String | |
| // ==== |
A lot of people mentioned other immutable JS libraries after reading my post. I thought it would be good to make a list of available ones.
There are two types of immutable libraries: simple helpers for copying JavaScript objects, and actual persistent data structure implementations. My post generally analyzed the tradeoffs between both kinds of libraries and everything applies to the below libraries in either category.
Libraries are sorted by github popularity.
| FROM node:0.12.7-wheezy | |
| # Install tools & libs to compile everything | |
| RUN apt-get update && apt-get install -y build-essential libssl-dev libreadline-dev wget && apt-get clean | |
| # Install imagemagick with support to native library | |
| RUN apt-get install -y imagemagick libmagick++-dev libmagic-dev && apt-get clean | |
| ENV PATH=$PATH:~/opt/bin:~/opt/node/bin:/usr/lib/x86_64-linux-gnu/ImageMagick-6.8.9/bin-Q16 | |
| # Install global CLIs |
| function mapValues(obj, fn) { | |
| return Object.keys(obj).reduce((result, key) => { | |
| result[key] = fn(obj[key], key); | |
| return result; | |
| }, {}); | |
| } | |
| function pick(obj, fn) { | |
| return Object.keys(obj).reduce((result, key) => { | |
| if (fn(obj[key])) { |
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