Object 可能是 null 反应/打字稿

Question

I keep running in to this error, the code works fine in plain react but in typescript it keeps throwing this error "Object is possibly null". I tried countering it using "." but it didn't help.

second error in the log says "cannot read properties of null reading (textContent) "

I set this to false

"strictNullChecks": false,

Here is a sandbox - https://codesandbox.io/s/sweet-mclean-nrhcdq?file=/src/App.tsx

This is the fetch api call -

const [isLoading, setLoading] = useState(false);
  //storing data
  const [data, setData] = useState(false);

  //fetching data
  useEffect(() => {
    setLoading(true);

    const fetchList = async (): Promise<UsersList> => {
      const result: any = await fetch("https://randomuser.me/api/?results=20")
        .then((res) => res.json())
        .then((data) => {
          setData(data);
          setLoading(false);
          console.log(data);
          
        });
        
      return result;
    };
    fetchList();
    
    
  }, []);

This is the code that is causing me the problem, is there a better way of doing this? someone mentioned useref but im not sure how to implement it with a fetch call in useEffect.

The desired output is for any text that includes Miss to have a blue background.

const h2 = window.document.getElementById("person")!
  h2.innerHTML = h2.textContent!.replace(/[Miss]/g, "<span class='title'>Miss</span>");

.title {
background-color: blue;
}

Later in the html I have filtered and mapped through the data -

<div style={hoverStyle} className="grid grid-cols-4 gap-2 p-2 mt-20">
        {data?.results.filter((val: any)=>{
          if (searchUser === "") {
            return val
          } else if (val.name.first.toLowerCase().includes(searchUser.toLowerCase())) { 
              return val          
          } else if (val.email.toLowerCase().includes(searchUser.toLowerCase())){
            return val
          } else if 
            (val.location.city.toLowerCase().includes(searchUser.toLowerCase())){
              return val
            } 
        }).map((d: any) => (
              
          <div style={hoverStyle} className=" ease-in-out delay-150 hover:-translate-y-1 hover:scale-110 duration-300  border-white shadow-slate-500 bg-white hover:opacity-95 rounded-lg container p-5">
            <img className="rounded-full w-44 h-44 " src={d.picture.large} />
            <h2 id="person" >{d.name.title}</h2>

Any ideas?

Answer 1

You are mapping through an array so it creates multiple h2 elements that is why need to select all h2 elements, also do that when data loading finished. try these changed lines.

 let h2 = document.querySelectorAll("h2")
  h2.innerHTML = !isLoading && h2.textContent?.replace(/[Miss]/g, "<span class='title'>Miss</span>");

Also here is the screen shot taken from your sandbox attached after doing that. Hope you are looking for the same.