gecko-dev/layout/style/test/test_rules_out_of_sheets.html

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<!DOCTYPE HTML>
<html>
<!--
https://bugzilla.mozilla.org/show_bug.cgi?id=634373
-->
<head>
<title>Test for Bug 634373</title>
<script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
<link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
</head>
<body>
<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=634373">Mozilla Bug 634373</a>
<p id="display"></p>
<div id="content" style="display: none">
</div>
<pre id="test">
<script type="application/javascript">
/** Test for Bug 634373 **/
function make_rule_and_remove_sheet(text, getter) {
var style = document.createElement("style");
style.setAttribute("type", "text/css");
style.appendChild(document.createTextNode(text));
document.head.appendChild(style);
var result = style.sheet.cssRules[0];
if (getter) {
result = getter(result);
}
document.head.removeChild(style);
style = null;
SpecialPowers.DOMWindowUtils.garbageCollect();
return result;
}
var gDisplayCS = getComputedStyle(document.getElementById("display"), "");
function keep_rule_alive_by_matching(rule) {
// It's the caller's job to guarantee that the rule matches a p.
// This just causes a style flush, which in turn keeps the rule alive
// until the next style flush.
var color = gDisplayCS.color;
return rule;
}
function get_rule_and_child(rule) {
return [rule, rule.cssRules[0]];
}
function get_only_child(rule) {
return rule.cssRules[0];
}
var rule;
// In this case, the rule goes away immediately, so we're testing
// the DOM wrapper's handling of a null rule, rather than the rule's
// handling of a null sheet.
rule = make_rule_and_remove_sheet("p { color: blue }");
rule.style.color = "";
try {
rule.style.color = "fuchsia";
} catch(ex) {}
rule = make_rule_and_remove_sheet("p { color: blue }",
keep_rule_alive_by_matching);
try {
rule.style.color = "";
} catch(ex) {}
try {
rule.style.color = "fuchsia";
} catch(ex) {}
rule = make_rule_and_remove_sheet("@media screen { p { color: blue } }",
get_rule_and_child);
rule[1].style.color = "";
try {
rule[1].style.color = "fuchsia";
} catch(ex) {}
// In this case, the rule goes away immediately, so we're testing
// the DOM wrapper's handling of a null rule, rather than the rule's
// handling of a null sheet.
rule = make_rule_and_remove_sheet("@media screen { p { color: blue } }",
get_only_child);
rule.style.color = "";
try {
rule.style.color = "fuchsia";
} catch(ex) {}
rule = make_rule_and_remove_sheet("@media screen { p { color: blue } }",
function(rule) {
return keep_rule_alive_by_matching(
get_only_child(rule));
});
try {
rule.style.color = "";
} catch(ex) {}
try {
rule.style.color = "fuchsia";
} catch(ex) {}
rule = make_rule_and_remove_sheet("@keyframes a { from { color: blue } }");
rule.appendRule("from { color: fuchsia}");
rule.deleteRule("from");
rule.name = "b";
rule.cssRules[0].keyText = "50%";
ok(true, "didn't crash");
</script>
</pre>
</body>
</html>