event.initEvent(type[, bubbles[, cancelable]])

• type <string>
• bubbles <boolean>
• cancelable <boolean>

与事件构造函数重复，并且无法设置 composed。这在 Node.js 中不使用，仅为完整性提供。

【Redundant with event constructors and incapable of setting composed. This is not used in Node.js and is provided purely for completeness.】