paulirish

What forces layout / reflow

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.

Element APIs

Getting box metrics

• elem.offsetLeft, elem.offsetTop, elem.offsetWidth, elem.offsetHeight, elem.offsetParent

mislav

Jim Weirich:

This is how I explain it… Ruby has Procs and Lambdas. Procs are created with Proc.new { }, lambdas are created with lambda {} and ->() {}.

In Ruby 1.8, proc {} creates lambda, and Ruby 1.9 it creates procs (don't ask).

Lambdas use method semantics when handling parameters, procs use assignment semantics when handling parameters.

This means lambdas, like methods, will raise an ArgumentError when called with fewer arguments than they were defined with. Procs will simply assign nil to variables for arguments that were not passed in.