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2020 前端面试题 —— DOM相关 #49

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fengmiaosen opened this issue May 6, 2020 · 0 comments

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fengmiaosen commented May 6, 2020

事件委托

事件委托就是利用事件冒泡，只指定一个事件处理程序，就可以管理某一类型的所有事件.
在绑定大量事件的时候往往选择事件委托。
- 优点：
  - 节省内存占用，减少事件注册
  - 新增子对象时无需再次对其绑定事件，适合动态添加元素
- 局限性
  - focus、blur 之类的事件本身没有事件冒泡机制，所以无法委托
  - mousemove、mouseout 这样的事件，虽然有事件冒泡，但是只能不断通过位置去计算定位，对性能消耗高，不适合事件委托

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