Suppose that we are displaying a large number of data, such as 10thousands of data, there is often a delay in puuting next value to the input field.
In this case, when we enter a value, the screen displays filtered data.
But then, a problem that occurs is the delay in displaying the next action such as input next value to input field due to handling too much data.
・src/Example.js
import { useState } from "react"; const generateDummyItem = (num) => { return new Array(num).fill(null).map((item, index) => `item ${index}`); }; const dummyItems = generateDummyItem(10000); const Example = () => { const [filterVal, setFilterVal] = useState(""); const changeHandler = (e) => { setFilterVal(e.target.value); }; return ( <> <input type="text" onChange={changeHandler} /> {isPending && <div>Loading...</div>} <ul> {dummyItems .filter((item) => { if (filterVal === "") return true; return item.includes(filterVal); }) .map((item) => ( <li key={item}>{item}</li> ))} </ul> </> ); }; export default Example; - To solve the problem, we can wrap the
setFilterValfunction with a startTransition.
const changeHandler = (e) => { startTransition(() => { setFilterVal(e.target.value); }) }; The startTransition makes a function delay to be executed within it.
Thanks to this feature, we can easily move on to the next value in the input field.
・Before input
・After input
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