13

Background

Assume we all know about the debounce function from lodash.

If a user quickly input 1,12,123,1234, it allows us to proceed an alert only once, with 1234, after a certain delay time.

This is quite used to reduce request amount, for optimization.

Description

For a normal input field, we can use that kind of debounce and it works.

Problem: Once we add a setState inside the same callback with debounce, the debounce won't work as normal.

Does anyone know the reason?

import React, { useState } from "react";
import "./styles.css";
import { debounce } from "lodash";

export default function App() {
  const [input, setInput] = useState("");

  const debouceRequest = debounce(value => {
    alert(`request: ${value}`);
  }, 1000);
  const onChange = e => {
    setInput(e.target.value); // Remove this line will lead to normal debounce
    debouceRequest(e.target.value);
  };

  return (
    <div className="App">
      <input onChange={onChange} />
    </div>
  );
}

Edit flamboyant-field-equct

keikai
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1 Answers1

14

Try this (using useCallback):

import React, { useState, useCallback } from "react";
import "./styles.css";
import { debounce } from "lodash";

const request = debounce(value => {
  alert(`request: ${value}`);
}, 1000);

export default function App() {
  const [input, setInput] = useState("");

  const debouceRequest = useCallback(value => request(value), []);

  const onChange = e => {
    debouceRequest(e.target.value);
    setInput(e.target.value); // Remove this line will lead to normal denounce
  };

  return (
    <div className="App">
      <input onChange={onChange} />
    </div>
  );
}

Edit elated-dawn-lb5ex

keikai
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Ehsan
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  • @keikai, could you help please with this https://stackoverflow.com/questions/66381227/change-the-state-according-to-event-in-reactjs – Asking Feb 26 '21 at 09:20
  • Can you update the answer to explain why this works? Is it because `debounce` uses `setTimeout()`, similar to https://stackoverflow.com/a/64856090/450127 ? – Ian Dunn Aug 30 '23 at 19:15