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Non-standard
This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.
getDefaultComputedStyle()
gives the default computed values of all the CSS properties of an element, ignoring author styling. That is, only user-agent and user styles are taken into account.
Syntax
var style = window.getDefaultComputedStyle(element[, pseudoElt]);
- element
- The
Element
for which to get the computed style. - pseudoElt Optional
- A string specifying the pseudo-element to match. Must be
null
(or not specified) for regular elements.
The returned style
is a CSSStyleDeclaration
object.
Example
var elem1 = document.getElementById("elemId"); var style = window.getDefaultComputedStyle(elem1);
<style> #elem-container { position: absolute; left: 100px; top: 200px; height: 100px; } </style> <div id="elem-container">dummy</div> <div id="output"></div> <script> var elem = document.getElementById("elem-container"); var theCSSprop = window.getDefaultComputedStyle(elem).position; document.getElementById("output").innerHTML = theCSSprop; // will output "static" </script>
Description
The returned object is of the same type as the object returned by getComputedStyle
, but only takes into account user-agent and user rules.
Use with pseudo-elements
getDefaultComputedStyle
can pull style info from pseudo-elements (for example, ::after
, ::before
).
<style> h3:after { content: ' rocks!'; } </style> <h3>generated content</h3> <script> var h3 = document.querySelector('h3'), result = getDefaultComputedStyle(h3, ':after').content; console.log('the generated content is: ', result); // returns 'none' </script>
Notes
The returned value is, in certain known cases, expressly incorrect by deliberate intent. In particular, to avoid the so called CSS History Leak security issue, browsers may expressly "lie" about the used value for a link and always return values as if a user has never visited the linked site, and/or limit the styles that can be applied using the :visited
pseudo-selector. See https://blog.mozilla.com/security/2010/03/31/plugging-the-css-history-leak/ and https://hacks.mozilla.org/2010/03/privacy-related-changes-coming-to-css-vistited/ for details of the examples of how this is implemented.
Specifications
Proposed to the CSS working group.
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
Basic support | Not supported | 19 | Not supported | Not supported | Not supported |
pseudo-element support | Not supported | 19 | Not supported | Not supported | Not supported |
Feature | Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|
Basic support | Not supported | 19 | 7.5 | Not supported | Not supported |
pseudo-element support | Not supported | 19 | Not supported | Not supported | Not supported |