HasLayout

what Layout?

“Layout” is an IE/Win proprietary concept that determines how elements draw and bound their content, interact with and relate to other elements, and react on and transmit application/user events.

why Layout?

A lot of Internet Explorer's rendering inconsistencies can be fixed by giving an element “layout.” Consequences of an element having, or not having “layout” can include:

• Many common IE float bugs.
• Boxes themselves treating basic properties differently.
• Margin collapsing between a container and its descendants.
• Various problems with the construction of lists.
• Differences in the positioning of background images.
• Differences between browsers when using scripting.

which element

body, html, table, tr, td, th, img, hr, input, button, file, select, textarea, fieldset, marquee, frameset, frame, iframe, objects, applets, embed

Those other properties are:

• display: inline-block ##Sometimes a cure when the element is at inline level and needs layout.
• height: (any value except auto)
• float: (left or right)
• position: absolute
• width: (any value except auto)
• writing-mode: tb-rl
• zoom: (any value except normal) ## always triggers hasLayout.

另外IE7

• min-height: (any value)

• max-height: (any value except none)

• min-width: (any value)

• max-width: (any value except none)

• overflow: (any value except visible)

• overflow-x: (any value except visible)

• overflow-y: (any value except visible)5

• position: fixed

  alert(eid.currentStyle.hasLayout)
  

Notes

• It's not a good idea to give all elements a layout.
• the standard approach for triggering an element to gain a layout in IE6, set height to 1% as long as the overflow property is not set to anything except visible. overflow设置为默认的visible, 容器高度会尽可能的撑开(不管设置的高度是多少), 其他浏览器会遵循height为1%, 所以这种方式只针对IE6.

IE下条件注释

• http://reference.sitepoint.com/css/conditionalcomments

  <!--[if IE ]>
  ...
  <![endif]-->
  
  if语句支持 lt, lte, gt, gte, !, &, (), |, true, false
  
  <!--[if !IE]>-->
  <p>...</p>
  <!--<![endif]-->
  

• http://reference.sitepoint.com/css/haslayout

• http://www.satzansatz.de/cssd/onhavinglayout.html 这里末尾有很多有关layout引起的问题例子.