beforescriptexecute 事件在一个脚本将要被执行时触发，它会取消事件防止脚本执行。
基本信息
- 规范
- HTML5 (WhatWG)
- 接口
- Event
- 冒泡
- Yes
- 可取消
- Yes
- 目标
- defaultView, Document, Element
- 默认动作
- None
属性（Properties）
| Property | Type | Description |
|---|---|---|
target 只读 |
EventTarget |
The script tag whose content is about to be executed. |
type 只读 |
DOMString |
The type of event. |
bubbles 只读 |
boolean |
Does the event normally bubble? |
cancelable 只读 |
boolean |
Is it possible to cancel the event? |