超过最大更新深度。 当组件在 useEffect 中调用 setState 时，可能会发生这种情况，

Question

 useEffect(() => { 
      const onChildAdd = database().ref('/User/' + user.uid ).on('value', snapshot => {
    setComplete(snapshot.val().Complete);
    setUserProfile(snapshot.val().User);  
    setStartYear(snapshot.val().StartYear);
     setDisplayName(snapshot.val().displayName);
    setDisplayPicture(snapshot.val().photoURL);
    // ...
    });
    
    
    return () =>
   database().ref('/User/' + user.uid  )
        .off('value', onChildAdd);


    }, [user.uid])

This is how each of them is used

<Text>My name is {displayName}</Text>

Error Warning: Maximum update depth exceeded. This can happen when a component calls setState inside useEffect, but useEffect either doesn't have a dependency array, or one of the dependencies changes on every render.

Answer 1

Are you using default value in code above this snippet?

if you do

const myComponent (props)=>{
    const {user = {}, stuff } = props; 

    {/* code here that accesses 'user' object inside hooks */}

    return <h1>Hi></h1>

}

A new object may be created for the 'user' variable on every render! Either use defaultprops or move the empty object creation out of the render loop

const empty = {};

const myComponent (props)=>{
    const {user = empty, stuff } = props; 

    {/* code here that accesses 'user' object inside hooks */}

    return <h1>Hi></h1>

}