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

tryashtar

Requirements

Selector arguments can optionally have two requirements: requiring only players, and requiring only a single target. Here are some examples of arguments of each type:

• Only players: /give <targets>
• Only a single target: /damage <target>
• Only a single player: /xp query <targets>
• Any number of any entities: /kill <targets>

As is well-known, each selector type has default "implicit" arguments. All behavior below will be described in terms of these arguments, not the base selectors themselves.

• @p, @a, and @r have an implicit type=player, and will fail to parse if given a different type.