React App显示props.location.state未定义

由蜡笔小新@发布于 2020-04-09 07:56:22

我在访问useEffect（）挂钩中的props.location.state时遇到麻烦。它是这样的：

useEffect((props) => {
    console.log("location: :", props.location.state); 
}, [props])

它显示props.location.state是未定义的。为什么它是未定义的，我该如何设置？

谢谢。

gqui

2020-04-09 07:56:22

I think you are using the props from callback, not that props what you want to use. You have to remove argument props from callback.

useEffect(() => {
    console.log("location: :", props.location.state); 
}, [props])

saut

2020-04-09 07:56:22

The second argument to useEffect is an array of values, the if any one of them changes, the effect should run. As a best practice, you should only put in values here that you need for the effect. I would change it to:

useEffect(() => {
    console.log("location: :", props.location.state); 
}, [props.location.state]);

Take a look at the React onEffect docs for more information: https://reactjs.org/docs/hooks-effect.html

蜡笔小新@

这家伙很懒，什么都没留下

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