| <!DOCTYPE html> |
| <meta charset="utf-8"> |
| <title>AddEventListenerOptions.once</title> |
| <link rel="author" title="Xidorn Quan" href="https://www.upsuper.org"> |
| <link rel="help" href="https://dom.spec.whatwg.org/#dom-addeventlisteneroptions-once"> |
| <script src="/resources/testharness.js"></script> |
| <script src="/resources/testharnessreport.js"></script> |
| <div id="log"></div> |
| <script> |
| |
| test(function() { |
| var invoked_once = false; |
| var invoked_normal = false; |
| function handler_once() { |
| invoked_once = true; |
| } |
| function handler_normal() { |
| invoked_normal = true; |
| } |
| |
| document.addEventListener('test', handler_once, {once: true}); |
| document.addEventListener('test', handler_normal); |
| document.dispatchEvent(new Event('test')); |
| assert_equals(invoked_once, true, "Once handler should be invoked"); |
| assert_equals(invoked_normal, true, "Normal handler should be invoked"); |
| |
| invoked_once = false; |
| invoked_normal = false; |
| document.dispatchEvent(new Event('test')); |
| assert_equals(invoked_once, false, "Once handler shouldn't be invoked again"); |
| assert_equals(invoked_normal, true, "Normal handler should be invoked again"); |
| document.removeEventListener('test', handler_normal); |
| }, "Once listener should be invoked only once"); |
| |
| test(function() { |
| var invoked_count = 0; |
| function handler() { |
| invoked_count++; |
| if (invoked_count == 1) |
| document.dispatchEvent(new Event('test')); |
| } |
| document.addEventListener('test', handler, {once: true}); |
| document.dispatchEvent(new Event('test')); |
| assert_equals(invoked_count, 1, "Once handler should only be invoked once"); |
| |
| invoked_count = 0; |
| function handler2() { |
| invoked_count++; |
| if (invoked_count == 1) |
| document.addEventListener('test', handler2, {once: true}); |
| if (invoked_count <= 2) |
| document.dispatchEvent(new Event('test')); |
| } |
| document.addEventListener('test', handler2, {once: true}); |
| document.dispatchEvent(new Event('test')); |
| assert_equals(invoked_count, 2, "Once handler should only be invoked once after each adding"); |
| }, "Once listener should be invoked only once even if the event is nested"); |
| |
| test(function() { |
| var invoked_count = 0; |
| function handler() { |
| invoked_count++; |
| } |
| |
| document.addEventListener('test', handler, {once: true}); |
| document.addEventListener('test', handler); |
| document.dispatchEvent(new Event('test')); |
| assert_equals(invoked_count, 1, "The handler should only be added once"); |
| |
| invoked_count = 0; |
| document.dispatchEvent(new Event('test')); |
| assert_equals(invoked_count, 0, "The handler was added as a once listener"); |
| |
| invoked_count = 0; |
| document.addEventListener('test', handler, {once: true}); |
| document.removeEventListener('test', handler); |
| document.dispatchEvent(new Event('test')); |
| assert_equals(invoked_count, 0, "The handler should have been removed"); |
| }, "Once listener should be added / removed like normal listeners"); |
| |
| test(function() { |
| var invoked_count = 0; |
| |
| for (let n = 4; n > 0; n--) { |
| document.addEventListener('test', (e) => { |
| invoked_count++; |
| e.stopImmediatePropagation(); |
| }, {once: true}); |
| } |
| |
| for (let n = 4; n > 0; n--) { |
| document.dispatchEvent(new Event('test')); |
| } |
| |
| assert_equals(invoked_count, 4, "The listeners should be invoked"); |
| }, "Multiple once listeners should be invoked even if the stopImmediatePropagation is set"); |
| |
| </script> |
