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Passing data from child component to parent component in React:

1. Pass the function as propa to the Child component.
2. Call the function in the Child component and pass the data as a parameter.
3. Access Parentdata in a function.

import {useState} from 'react';

function Child({handleClick}) {
  return (
    <div>
      <button onClick={event => handleClick(100)}>Click</button>
    </div>
  );
}

export default function Parent() {
  const [count, setCount] = useState(0);

  const handleClick = num => {
    // 👇️ take parameter passed from Child component
    setCount(current => current + num);
  };

  return (
    <div>
      <Child handleClick={handleClick} />

      <h2>Count: {count}</h2>
    </div>
  );
}

ParentThe component defines a handleClickfunction that takes a num parameter.

We pass that function as a prop to Childthe component, so Childwe are able to call the function and pass it any data we need to access in the Parent.

When the Child's button element is clicked, the handleClick function is called and the parameters we passed to that function are accessible in the Parent component.

We may also need to include the event object in the function's arguments.

import {useState} from 'react';

function Child({handleClick}) {
  return (
    <div>
      <button onClick={event => handleClick(event, 100)}>
        Click
      </button>
    </div>
  );
}

export default function Parent() {
  const [count, setCount] = useState(0);

  const handleClick = (event, num) => {
    console.log(event.target);

    setCount(current => current + num);
  };

  return (
    <div>
      <Child handleClick={handleClick} />

      <h2>Count: {count}</h2>
    </div>
  );
}

Now handleClickthe function takes the event object and a number as parameters, and the child component forwards the event to the parent component.

We can use this method to pass anything from child component to parent component.

All we have to do is pass a function prop to Childand Childcall that function in the component, Parentpassing it the data we need to access in as arguments.