windowproxy-prevent-extensions.html (633B)
1 <!DOCTYPE html> 2 <meta charset="utf-8"> 3 <title>[[PreventExtensions]] on a WindowProxy object should return false</title> 4 <link rel="help" href="https://html.spec.whatwg.org/multipage/window-object.html#windowproxy-preventextensions"> 5 6 <script src="/resources/testharness.js"></script> 7 <script src="/resources/testharnessreport.js"></script> 8 9 <script> 10 "use strict"; 11 12 test(() => { 13 assert_throws_js(TypeError, () => { 14 Object.preventExtensions(window); 15 }); 16 }, "Object.preventExtensions throws a TypeError"); 17 18 test(() => { 19 assert_false(Reflect.preventExtensions(window)); 20 }, "Reflect.preventExtensions returns false"); 21 </script>