From 0ccebc7eb352eda4d26d0b876fea36f24f482eec Mon Sep 17 00:00:00 2001 From: MDN Date: Sat, 17 Apr 2021 00:11:36 +0000 Subject: [CRON] sync translated content --- .../creating_and_triggering_events/index.html | 136 --------------------- 1 file changed, 136 deletions(-) delete mode 100644 files/zh-cn/web/guide/events/creating_and_triggering_events/index.html (limited to 'files/zh-cn/web/guide') diff --git a/files/zh-cn/web/guide/events/creating_and_triggering_events/index.html b/files/zh-cn/web/guide/events/creating_and_triggering_events/index.html deleted file mode 100644 index 65249da219..0000000000 --- a/files/zh-cn/web/guide/events/creating_and_triggering_events/index.html +++ /dev/null @@ -1,136 +0,0 @@ ---- -title: 创建和触发 events -slug: Web/Guide/Events/Creating_and_triggering_events -tags: - - Advanced - - DOM - - Guide - - events -translation_of: Web/Guide/Events/Creating_and_triggering_events ---- -

本文演示了如何创建和分派DOM事件。这些事件通常称为合成事件，而不是浏览器本身触发的事件。

- -

创建自定义事件

- -

Events 可以使用 Event 构造函数创建如下：

- -
var event = new Event('build');
-
-// Listen for the event.
-elem.addEventListener('build', function (e) { ... }, false);
-
-// Dispatch the event.
-elem.dispatchEvent(event);
- -

上述代码使用了 EventTarget.dispatchEvent() 方法。

- -

绝大多数现代浏览器中都会支持这个构造函数（Internet Explorer 例外）。 要了解更为复杂的方法，可参考下面的 过时的方式  一节。

- -

添加自定义数据 – CustomEvent()

- -

要向事件对象添加更多数据，可以使用 CustomEvent 接口，detail 属性可用于传递自定义数据。
- 例如，event 可以创建如下：

- -
var event = new CustomEvent('build', { 'detail': elem.dataset.time });
- -

下面的代码允许你在事件监听器中访问更多的数据：

- -
function eventHandler(e) {
-  log('The time is: ' + e.detail);
-}
-
- -

过时的方式

- -

早期的创建事件的方法使用了受Java启发的API。下面展示了一个示例：

- -
// Create the event.
-var event = document.createEvent('Event');
-
-// Define that the event name is 'build'.
-event.initEvent('build', true, true);
-
-// Listen for the event.
-document.addEventListener('build', function (e) {
-  // e.target matches document from above
-}, false);
-
-// target can be any Element or other EventTarget.
-document.dispatchEvent(event);
-
- -

事件冒泡

- -

通常需要从子元素触发事件，并让祖先捕获它：

- -
<form>
-  <textarea></textarea>
-</form>
- -
const form = document.querySelector('form');
-const textarea = document.querySelector('textarea');
-
-// Create a new event, allow bubbling, and provide any data you want to pass to the "details" property
-const eventAwesome = new CustomEvent('awesome', {
-  bubbles: true,
-  detail: { text: () => textarea.value }
-});
-
-// The form element listens for the custom "awesome" event and then consoles the output of the passed text() method
-form.addEventListener('awesome', e => console.log(e.detail.text()));
-
-// As the user types, the textarea inside the form dispatches/triggers the event to fire, and uses itself as the starting point
-textarea.addEventListener('input', e => e.target.dispatchEvent(eventAwesome));
- -

动态创建和派发事件

- -

元素可以侦听尚未创建的事件：

- -
<form>
-  <textarea></textarea>
-</form>
- -
const form = document.querySelector('form');
-const textarea = document.querySelector('textarea');
-
-form.addEventListener('awesome', e => console.log(e.detail.text()));
-
-textarea.addEventListener('input', function() {
-  // Create and dispatch/trigger an event on the fly
-  // Note: Optionally, we've also leveraged the "function expression" (instead of the "arrow function expression") so "this" will represent the element
-  this.dispatchEvent(new CustomEvent('awesome', { bubbles: true, detail: { text: () => textarea.value } }))
-});
- - - -

触发内置事件

- -

下面的例子演示了一个在复选框上点击（click）的模拟（就是说在程序里生成一个click事件），这个模拟点击使用了DOM方法。参见这个动态示例

- -
function simulateClick() {
-  var event = new MouseEvent('click', {
-    'view': window,
-    'bubbles': true,
-    'cancelable': true
-  });
-  var cb = document.getElementById('checkbox');
-  var cancelled = !cb.dispatchEvent(event);
-  if (cancelled) {
-    // A handler called preventDefault.
-    alert("cancelled");
-  } else {
-    // None of the handlers called preventDefault.
-    alert("not cancelled");
-  }
-}
-
- -

参见

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