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A Custom React Hook that handles duplicate API call

AnxinYang
A front-end developer.
・1 min read

Today, we are going to create a custom hook that solve this problem:

  • We have multiple components that calling same API.
  • Component may not always be on same page, therefore, they have to call the API by themselves.

Here is a example hook I think can handle this problem:

let isCalling = new Map(); // This can be replace by some global state. I use this for the sake of simplicity.
function useFetch(url) {
  const [data, setData] = useState("");
  useEffect(() => {
    let isThisAPICalling = isCalling.get(url);
    if (!isThisAPICalling) {
      console.log("new");
      isThisAPICalling = fetch(url).then((response) => response.json());
      isCalling.set(url, isThisAPICalling);
      // The body can only be parsed once.
    }
    isThisAPICalling.then((json) => {
      console.log("done");
      console.log(json.title);
      isCalling.delete(url);
      setData(json.title);
    });
  }, []);
  return data;
}
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Here is a demo.

Thank you all! Please let me know if you have any suggestion.

Discussion (2)

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alfredosalzillo profile image
Alfredo Salzillo 🐺

Maybe you wanted to implement an useDebounce

GitHub logo xnimorz / use-debounce

A debounce hook for react

Features

Install

yarn add use-debounce
# or
npm i use-debounce --save
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Demos

The simplest way to start playing around with use-debounce is with this CodeSandbox snippet codesandbox.io/s/kx75xzyrq7

More complex example with searching for matching countries using debounced input: codesandbox.io/s/rr40wnropq (thanks to twitter.com/ZephDavies)

Changelog

github.com/xnimorz/use-debounce/bl...

Simple values debouncing

According to twitter.com/dan_abramov/status/106...

import React, { useState } from 'react';
import { useDebounce } from 'use-debounce';
export default function Input() {
  const [text, setText] = useState('Hello');
  const [value] = useDebounce(text, 1000);
  return (
    <div>
      <input
        defaultValue={'Hello'}
        onChange={(e) => {
          setText(e.target.value);
        }}
      />
      <p>Actual value: {text}</
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anxinyang profile image
AnxinYang Author

Thanks for replying.

But I feel like this is for the function that is repeatly called in one component.
Here is multiple components calling same api.

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