css/css-variables/variable-reference-shorthands-cssom.html

<!DOCTYPE html>
<html>
<head>
    <title>CSS variable references - shorthand properties - via CSSOM</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/#serializing-custom-props">

    <script src="/resources/testharness.js"></script>
    <script src="/resources/testharnessreport.js"></script>
</head>
<body>

<div id="target"></div>

<script type="text/javascript">
    "use strict";

    function runTest() {
        var target = document.getElementById("target");

        target.style.setProperty("margin", "var(--prop)");
        assert_equals(target.style.margin, "var(--prop)", "margin property value after calling setProperty");
        assert_equals(target.style.getPropertyValue("margin"), "var(--prop)", "getPropertyValue('margin') after calling setProperty");

        target.style.removeProperty("margin");
        assert_equals(target.style.margin, "", "margin property value after calling removeProperty");
        assert_equals(target.style.getPropertyValue("margin"), "", "getPropertyValue('margin') after calling removeProperty");
    }

    test(runTest);
</script>

</body>
</html>