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
(by @andrestaltz)
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| # Run this in the project repo from the command-line | |
| # http://stackoverflow.com/a/4593065/99923 | |
| git log --shortstat --author "Xeoncross" --since "2 weeks ago" --until "1 week ago" | grep "files changed" | awk '{files+=$1; inserted+=$4; deleted+=$6} END {print "files changed", files, "lines inserted:", inserted, "lines deleted:", deleted}' |
| Latency Comparison Numbers (~2012) | |
| ---------------------------------- | |
| L1 cache reference 0.5 ns | |
| Branch mispredict 5 ns | |
| L2 cache reference 7 ns 14x L1 cache | |
| Mutex lock/unlock 25 ns | |
| Main memory reference 100 ns 20x L2 cache, 200x L1 cache | |
| Compress 1K bytes with Zippy 3,000 ns 3 us | |
| Send 1K bytes over 1 Gbps network 10,000 ns 10 us | |
| Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD |
| =Navigating= | |
| visit('/projects') | |
| visit(post_comments_path(post)) | |
| =Clicking links and buttons= | |
| click_link('id-of-link') | |
| click_link('Link Text') | |
| click_button('Save') | |
| click('Link Text') # Click either a link or a button | |
| click('Button Value') |