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React side effect

Mozahedul Islam answered on March 26, 2023 Popularity 9/10 Helpfulness 4/10

answer React side effect

React side effect

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What do you mean by react side effect? 
In React, a "side effect" refers to any code that has an effect outside of the component itself, such as changing the DOM, making an HTTP request, or setting up a timer. Side effects are typically performed in a React component using the useEffect hook.

The useEffect hook allows you to run side effects after a component has rendered or when certain dependencies have changed. The hook takes two arguments: a function that performs the side effect, and an optional array of dependencies that determines when the effect should run.
Here's an example of a side effect that fetches data from an API:

import React, { useState, useEffect } from 'react';

function ExampleComponent() {
  const [data, setData] = useState([]);

  useEffect(() => {
    fetch('https://example.com/api/data')
      .then(response => response.json())
      .then(data => setData(data));
  }, []); // <-- Empty dependency array means the effect runs only once

  return (
    <div>
      {data.map(item => (
        <div key={item.id}>{item.name}</div>
      ))}
    </div>
  );
}
In this example, the useEffect hook fetches data from an API using the fetch function. The hook also sets the data state variable with the results of the API call. The effect runs only once, because the dependency array is empty.

Note that the fetch function is a side effect because it has an effect outside of the component itself. Specifically, it sends an HTTP request to an external API and returns a response. Without the useEffect hook, this side effect would be difficult to perform in a React component, because components are designed to be "pure" and not have side effects.

Overall, side effects are an important concept in React because they allow you to interact with the outside world, such as APIs or the DOM, while still maintaining a declarative and component-based programming model.

Popularity 9/10 Helpfulness 4/10 Language javascript

Source: Grepper

Tags: effect javascript

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Contributed on Mar 26 2023

Mozahedul Islam

0 Answers Avg Quality 2/10

React side effect

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