prefers-contrast.html

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This WPT test may be referenced by the following Test IDs:
- /css/mediaqueries/prefers-contrast.html - WPT Dashboard Interop Dashboard

<!DOCTYPE html>

<link rel="help" href="https://drafts.csswg.org/mediaqueries-5/#prefers-contrast" />

<script type="text/javascript" src="/resources/testharness.js"></script>

<script type="text/javascript" src="/resources/testharnessreport.js"></script>

<script type="text/javascript" src="resources/matchmedia-utils.js"></script>

<script>

query_should_be_known("(prefers-contrast)");

query_should_be_known("(prefers-contrast: no-preference)");

query_should_be_known("(prefers-contrast: more)");

query_should_be_known("(prefers-contrast: less)");

query_should_be_known("(prefers-contrast: custom)");

query_should_be_unknown("(prefers-contrast: increase)");

query_should_be_unknown("(prefers-contrast: none)");

query_should_be_unknown("(prefers-contrast: forced high)");

query_should_be_unknown("(prefers-contrast: forced low)");

query_should_be_unknown("(prefers-contrast > increase)");

query_should_be_unknown("(prefers-increased-contrast)");

query_should_be_unknown("(prefers-decreased-contrast)");

query_should_be_unknown("(prefers-contrast: high)");

query_should_be_unknown("(prefers-contrast: low)");

query_should_be_unknown("(prefers-contrast: forced)");

test(() => {

  // no-preference is the default and all other values evaluate to

  // true in the boolean context. If no-preference matches, then

  // boolean context should be false. If no-preference does not match

  // then boolean context should be true. Therefore, these two values

  // should always be each others inverse irrespective of OS level

  // settings.

  let booleanContext = window.matchMedia("(prefers-contrast)");

  let noPref = window.matchMedia("(prefers-contrast: no-preference)");

  assert_equals(noPref.matches, !booleanContext.matches);

}, "Check boolean context evaluation.");

</script>