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diff --git a/files/zh-cn/web/events/creating_and_triggering_events/index.html b/files/zh-cn/web/events/creating_and_triggering_events/index.html new file mode 100644 index 0000000000..686d6471af --- /dev/null +++ b/files/zh-cn/web/events/creating_and_triggering_events/index.html @@ -0,0 +1,138 @@ +--- +title: 创建和触发 events +slug: Web/Events/Creating_and_triggering_events +translation_of: Web/Events/Creating_and_triggering_events +tags: + - Advanced + - DOM + - Guide + - JavaScript + - NeedsContent + - events +--- +<p>本文演示了如何创建和分派DOM事件。这些事件通常称为<strong>合成事件</strong>，而不是浏览器本身触发的事件。</p> + +<h2 id="创建自定义事件">创建自定义事件</h2> + +<p>Events 可以使用 <a href="/zh/docs/Web/API/Event"><code>Event</code></a> 构造函数创建如下：</p> + +<pre class="brush: js">var event = new Event('build'); + +// Listen for the event. +elem.addEventListener('build', function (e) { ... }, false); + +// Dispatch the event. +elem.dispatchEvent(event);</pre> + +<p>上述代码使用了 <a href="https://wiki.developer.mozilla.org/en-US/docs/Web/API/EventTarget/dispatchEvent">EventTarget.dispatchEvent()</a> 方法。</p> + +<p><span style="line-height: 1.5;">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 </span><a href="#The_old-fashioned_way" style="line-height: 1.5;" title="#过时的方式">过时的方式</a><span style="line-height: 1.5;"> 一节。</span></p> + +<h3 id="添加自定义数据_–_CustomEvent">添加自定义数据 – CustomEvent()</h3> + +<p>要向事件对象添加更多数据，可以使用 <a href="/zh-CN/docs/Web/API/CustomEvent">CustomEvent</a> 接口，detail 属性可用于传递自定义数据。<br> + 例如，event 可以创建如下：</p> + +<pre class="brush: js">var event = new CustomEvent('build', { 'detail': elem.dataset.time });</pre> + +<p><span style="line-height: 1.5;">下面的代码允许你在事件监听器中访问更多的数据：</span></p> + +<pre class="brush: js">function eventHandler(e) { + log('The time is: ' + e.detail); +} +</pre> + +<h3 id="过时的方式">过时的方式</h3> + +<p>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：</p> + +<pre class="brush: js">// 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); +</pre> + +<h3 id="事件冒泡">事件冒泡</h3> + +<p>通常需要从子元素触发事件，并让祖先捕获它：</p> + +<pre class="brush: html"><form> + <textarea></textarea> +</form></pre> + +<pre class="brush: js">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));</pre> + +<h3 id="动态创建和派发事件">动态创建和派发事件</h3> + +<p>元素可以侦听尚未创建的事件：</p> + +<pre class="brush: html"><code><form> + <textarea></textarea> +</form></code></pre> + +<pre class="brush: js">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 } })) +});</pre> + + + +<h2 id="触发内置事件">触发内置事件</h2> + +<p>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。<a href="http://developer.mozilla.org/samples/domref/dispatchEvent.html">参见这个动态示例</a></p> + +<pre class="brush: js">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"); + } +} +</pre> + +<h2 id="Browser_compatibility" name="Browser_compatibility">参见</h2> + +<ul> + <li><a href="https://developer.mozilla.org/en-US/docs/Web/API/CustomEvent/CustomEvent">CustomEvent()</a></li> + <li>{{domxref("document.createEvent()")}}</li> + <li>{{domxref("Event.initEvent()")}}</li> + <li>{{domxref("EventTarget.dispatchEvent()")}}</li> + <li>{{domxref("EventTarget.addEventListener()")}}</li> +</ul> |