Why does adding useState result in a white screen in my react app?
Question
The code below works completely fine and results in the image below.
import React from "react";
import "./App.css";
import { useState } from "react";
function App(){
return(
<body>
<div className="nav_bar">
<link href="https://fonts.googleapis.com/icon?family=Material+Icons" rel="stylesheet"></link>
<ul className="top">
<div className="circle circle1">
<li className="material-icons noselect">
drag_handle
</li>
</div>
<div className="circle circle2">
<li className="material-icons noselect">
home
</li>
</div>
<div className="circle circle3">
<li className="material-icons noselect">
person_outline
</li>
</div>
</ul>
<nav>
<ul className="bottom">
<li className="material-icons noselect" id="feed-bottom">
drag_handle
</li>
<li className="material-icons noselect" id="home-bottom">
home
</li>
<li className="material-icons noselect" id="profile-bottom">
person_outline
</li>
</ul>
</nav>
</div>
</body>
);
}
export default App;
Adding useState to get and set the current state causes the navbar to disappear and show a completely white screen. Specifically I am using useState to change the icon shown in the nav bar to text and to set the currernt state to the icon that is clicked. Code Below
import React from "react";
import "./App.css";
import { useState } from "react";
function App(){
const[selected, setselected] = useState('home');
if(selected === 'feed'){
const feed = document.getElementById('feed-bottom');
feed.innerHTML = 'FEED';
} else if (selected === 'profile') {
const profile = document.getElementById('profile-bottom');
profile.innerHTML = 'PROFILE';
}else{
const home = document.getElementById('home-bottom');
home.innerHTML = 'HOME';
}
return(
<body>
<div className="nav_bar">
<link href="https://fonts.googleapis.com/icon?family=Material+Icons" rel="stylesheet"></link>
<ul className="top">
<div className="circle circle1">
<li className="material-icons noselect">
drag_handle
</li>
</div>
<div className="circle circle2">
<li className="material-icons noselect">
home
</li>
</div>
<div className="circle circle3">
<li className="material-icons noselect">
person_outline
</li>
</div>
</ul>
<nav>
<ul className="bottom">
<li className="material-icons noselect" id="feed-bottom" onClick={setselected('profile')}>
drag_handle
</li>
<li className="material-icons noselect" id="home-bottom" onClick={setselected('home')}>
home
</li>
<li className="material-icons noselect" id="profile-bottom" onClick={setselected('profile')}>
person_outline
</li>
</ul>
</nav>
</div>
</body>
);
}
export default App;
I've looked up many post that refernece similar issues but couldn't find one that pretained to mine. I would grealty appreciate some assitance.
1 answers
solution1
2 ACCPTED 2022-08-15 02:42:43
This line
home.innerHTML = 'HOME';
will cause an error on mount, because on mount, the React elements returned from App haven't been returned yet - the container is still empty; the #feed-bottom element doesn't exist yet.
While you could fix it by only assigning if the element actually exists, it would be far better to do it the React way and put the values conditionally into the JSX. Don't use vanilla DOM methods in React unless you absolutely have to.
Another problem is that your listeners - eg onClick={setselected('home')} - run when computed (immediately), because you're invoking the setselected function instead of passing a function as a prop to onClick .
You also probably meant to pass feed in the feed-bottom element (instead of profile ).
To implement your logic in the React way, you need something like:
<li className="material-icons noselect" id="feed-bottom" onClick={() => setselected('feed')}>
{ selected === 'feed' ? 'FEED' : 'drag_handle' }
</li>
<li className="material-icons noselect" id="home-bottom" onClick={() => setselected('home')}>
{ selected === 'home' ? 'HOME' : 'home' }
home
</li>
<li className="material-icons noselect" id="profile-bottom" onClick={() => setselected('profile')}>
{ selected === 'profile' ? 'PROFILE' : 'person_outline' }
person_outline
</li>
and remove all of the if(selected === 'feed'){ and the like code from the top.
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