add object to array usestate code example

Example 1: usestate array push

setTheArray([...theArray, newElement]);

Example 2: How to add object in an array using useState

import React, { useState } from 'react';
 
function App() {
 
  const [items, setItems] = useState([]);
 
  // handle click event of the button to add item
  const addMoreItem = () => {
    setItems(prevItems => [...prevItems, {
      id: prevItems.length,
      value: getRandomNumber()
    }]);
  }
 
  // generate 6 digit random number
  const getRandomNumber = () => {
    return Math.random().toString().substring(2, 8);
  }
 
  return (
    <div classname="App">
      <h3>useState with an array in React Hooks - <a href="https://www.cluemediator.com">Clue Mediator</a></h3>
      <br>
      <button onclick="{addMoreItem}">Add More</button>
      <br><br>
      <label>Output:</label>
      <pre>{JSON.stringify(items, null, 2)}</pre>
    </div>
  );
}
 
export default App;

Example 3: functional component how to add to existing array react

const {useState, useCallback} = React;
function Example() {
    const [theArray, setTheArray] = useState([]);
    const addEntryClick = () => {
        setTheArray([...theArray, `Entry ${theArray.length}`]);
    };
    return [
        <input type="button" onClick={addEntryClick} value="Add" />,
        <div>{theArray.map(entry =>
          <div>{entry}</div>
        )}
        </div>
    ];
}

ReactDOM.render(
    <Example />,
    document.getElementById("root")
);

Example 4: add object to array setstate

To push to the beginning of the array do it this way

   this.setState( prevState => ({
     userFavorites: [{id: 3, title: 'C'}, ...prevState.userFavourites]
  }));

Example 5: add object to array react hook

setTheArray([...theArray, newElement]);