A document created through parseFromString inherits creator document's CSS #15389

freeatnet · 2017-02-04T23:09:14Z

Steps to reproduce:

Open a document that contains one or more CSS rules and creates a non-empty document using DOMParser.parseFromString
Check the result of window.getComputedStyle on the created document

Expected: created document does not inherit CSS rules of the main document
Observed: created document inherits CSS rules of the main document

The issue can be reproduced using the following test:

<!doctype html>
<meta charset="utf-8">
<title></title>
<body>
  <style>
    div {
      background-color: yellow;
    }
  </style>

  <div>I'm inside the form!</div>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script>
var newDocHtml = '<html><body><div></div></body></html>';

/* This test succeeds */
test(function () {
  var d = (new DOMParser).parseFromString(newDocHtml, 'text/html');

  assert_equals(document.styleSheets.length, 1);
  assert_equals(d.styleSheets.length, 0);
}, "Count styleSheets correctly");

/* This test fails */
test(function () {
  var d = (new DOMParser).parseFromString(newDocHtml, 'text/html');
  var dd = d.getElementsByTagName('div')[0];

  assert_equals(window.getComputedStyle(dd).getPropertyValue("background-color"), '');
}, "Apply styleSheets correctly");
</script>
</body>

jdm · 2017-02-04T23:20:59Z

Interestingly enough, there's a note about this specific case in https://drafts.csswg.org/cssom/#dom-window-getcomputedstyle:

Note: This means that even if obj is in a different document (e.g. one fetched via 
XMLHttpRequest) it will still use the style rules associated with the document that is associated 
with the global object on which getComputedStyle() was invoked to compute the CSS declaration 
block.

jdm · 2017-02-04T23:24:26Z

Doubly interestingly, there's code that deals with a similar case which has an interesting TODO comment that suggests that the spec may not be aligned with the real world: https://dxr.mozilla.org/servo/rev/da89099e26955cf5ba44031a0a536e3af4e6a0d5/components/script/dom/cssstyledeclaration.rs#201-205

jdm added the A-content/dom label Feb 4, 2017

jdm added C-has-manual-testcase I-spec-unclear labels Feb 4, 2017

servo / servo

A document created through parseFromString inherits creator document's CSS #15389

A document created through parseFromString inherits creator document's CSS #15389

freeatnet commented Feb 4, 2017

jdm commented Feb 4, 2017 •

edited

jdm commented Feb 4, 2017

servo / servo

Join GitHub today

A document created through parseFromString inherits creator document's CSS #15389

A document created through parseFromString inherits creator document's CSS #15389

Comments

freeatnet commented Feb 4, 2017

jdm commented Feb 4, 2017 • edited

jdm commented Feb 4, 2017

jdm commented Feb 4, 2017 •

edited