Kevin EmperorEarth

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

scrollIntoViewIfNeeded 4 everyone!!!

This gist provides a simple JavaScript implementation of the non-standard WebKit method scrollIntoViewIfNeeded that can be called on DOM elements.

Usage

Just use the code in index.js in your app or website. You can see usage in the test page test.html.

The parent element will only scroll if the element being called is out of the view. The boolean can force the element to be centered in the scrolling area.

	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

	# Mac OS X Lion introduced a new, iOS-like context menu when you press and hold a key
	# that enables you to choose a character from a menu of options. If you are on Lion
	# try it by pressing and holding down 'e' in any app that uses the default NSTextField
	# for input.
	#
	# It's a nice feature and continues the blending of Mac OS X and iOS features. However,
	# it's a nightmare to deal with in Sublime Text if you're running Vintage (Vim) mode,
	# as it means you cannot press and hold h/j/k/l to move through your file. You have
	# to repeatedly press the keys to navigate.