<!DOCTYPE html>
<html>
<head>
<title>CSS Variables - Transitions - Variable value specified before transition; variable specified by name</title>
<meta rel="author" title="Kevin Babbitt">
<meta rel="author" title="Greg Whitworth">
<link rel="author" title="Microsoft Corporation" href="http://microsoft.com" />
<link rel="help" href="http://www.w3.org/TR/css-variables-1/#syntax">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
#target
{
--value: blue;
color: var(--value);
}
#target
{
transition-property: --value;
transition-duration: 1s;
}
#target.changed
{
--value: green;
}
</style>
</head>
<body>
<div id="target">This text should transition from blue to green over a period of 1 second.</div>
<script type="text/javascript">
"use strict";
// Force an initial layout pass
document.documentElement.offsetHeight;
test(function() {
assert_equals(window.getComputedStyle(document.getElementById("target")).getPropertyValue("--value").trim(), "blue", "--value is blue before transition runs");
}, "Verify CSS variable value before transition");
test(function() {
assert_equals(window.getComputedStyle(document.getElementById("target")).getPropertyValue("color").trim(), "rgb(0, 0, 255)", "color is blue before transition runs");
}, "Verify substituted color value before transition");
var afterAnimationVariableTest = async_test("Verify CSS variable value after transition");
document.getElementById("target").addEventListener("transitionend", afterAnimationVariableTest.step_func_done(function() {
assert_equals(window.getComputedStyle(document.getElementById("target")).getPropertyValue("--value").trim(), "green", "--value is green after transition runs")
}));
var afterAnimationColorTest = async_test("Verify substituted color value after transition");
document.getElementById("target").addEventListener("transitionend", afterAnimationColorTest.step_func_done(function() {
assert_equals(window.getComputedStyle(document.getElementById("target")).getPropertyValue("color").trim(), "rgb(0, 128, 0)", "color is green after transition runs")
}));
// Trigger transition
document.getElementById("target").className = "changed";
// Force another layout pass
document.documentElement.offsetHeight;
</script>
</body>
</html>