如何在箭头功能内访问Argument对象 [英] How to access Argument object inside arrow function

问题描述

listOfArg函数中的自变量Object引用带有箭头功能的父arguments.而且，如果没有箭头功能，this键的引用将发生更改，并且listOfArg函数将无法通过this更改进行访问.

The arguments Object inside listOfArg function refers to parent arguments with arrow function. And without arrow function this key reference would change and listOfArg function will no longer accessible through this change.

componentDidMount(){
      document.addEventListener('scroll', this.onScrollEvent);
  }

listOfArg = () => {
    console.log(arguments)
  }

onScrollEvent = (e) => {
     this.listOfArg("1", "2", "3", "4")
}

推荐答案

来自 MDN文档

箭头函数没有自己的this；使用封闭执行上下文的this值.

An arrow function does not have its own this; the this value of the enclosing execution context is used.

如果您使用

listOfArg = () => {
    console.log(arguments)
}

onScrollEvent中的

this将引用组件this，并且您将获得传递给该组件的参数，因为箭头函数将使用封闭的执行上下文，即React组件.

this inside onScrollEvent would refer to the component this and you would get arguments passed to the component because arrow function would use enclosing execution context which is the React Component.

现在，如果您不使用箭头功能:

Now, if you do not use arrow function:

listOfArg() {
  console.log(arguments)
}

在这里，listOfArg将有其自己的this，并会打印调用它的参数:["1", "2", ...]，这是预期的.

Here, listOfArg will have its own this and would print arguments it was called with: ["1", "2", ...] which is expected.

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