Event.cancelable

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cancelable 只读特性在 事件 interface indicates whether the event can be canceled, and therefore prevented as if the event never happened. If the event is not cancelable, then its cancelable property will be false and the event listener cannot stop the event from occurring.

Event listeners that handle multiple kinds of events may want to check cancelable before invoking their preventDefault() 方法。

Most browser-native events that can be canceled are the ones that result from the user interacting with the page. Canceling the click , scroll ，或 beforeunload events would prevent the user from clicking on something, scrolling the page, or navigating away from the page, respectively.

Custom events created by other JavaScript code control if they can be canceled when they are created.

句法

bool = event.cancelable;

值

The result is a 布尔 ，其是 true if the event can be canceled.

范例

For example, browser vendors are proposing that the wheel event can only be canceled the first time the listener is called — any following wheel events cannot be canceled.

function preventScrollWheel(event) {
  if (typeof event.cancelable !== 'boolean' || event.cancelable) {
    // The event can be canceled, so we do so.
    event.preventDefault();
  } else {
    // The event cannot be canceled, so it is not safe
    // to call preventDefault() on it.
    console.warn(`The following event couldn't be canceled:`);
    console.dir(event);
  }
}
document.addEventListener('wheel', preventScrollWheel);

注意事项

Whether an event can be canceled or not is something that's determined when that event is initialized.

To cancel an event, call the preventDefault() method on the event. This keeps the implementation from executing the default action that is associated with the event.

规范

规范	状态	注释
DOM The definition of 'Event.cancelable' in that specification.	实时标准
DOM (文档对象模型) 2 级事件规范 The definition of 'Event.cancelable' in that specification.	过时	初始定义。

浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. 更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`cancelable`	Chrome Yes	Edge 12	Firefox Yes	IE ?	Opera Yes	Safari Yes	WebView Android Yes	Chrome Android Yes	Firefox Android Yes	Opera Android Yes	Safari iOS Yes	Samsung Internet Android Yes

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元数据

最后修改： Feb 19, 2020

DOM (文档对象模型)
事件
构造函数
1. 事件
特性
1. bubbles
2. cancelable
3. cancelBubble
4. composed
5. currentTarget
6. defaultPrevented
7. eventPhase
8. explicitOriginalTarget
9. isTrusted
10. originalTarget
11. returnValue
12. srcElement
13. target
14. timeStamp
15. type
方法
事件
1. bubbles
2. cancelable
3. cancelBubble
4. composed
5. composedPath
6. currentTarget
7. defaultPrevented
8. 事件
9. eventPhase
10. initEvent
11. isTrusted
12. preventDefault
13. returnValue
14. stopImmediatePropagation
15. stopPropagation
16. target
17. timeStamp
18. type
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