React: How to pass input value to parent component

MrRobot 0
Viewed 42

I'm new to React and I'm stuck with something.

I have 3 components, Home, UserForm and Input, they're nested as described. I need to have the values of the input as the user types on the home component. I can't get it to work.

I need help!

home.jsx

import React from 'react';

import UserForm from '../components/UserForm';

import './Home.scss';

export default function Home() {

    return (
        <div className="home-container">
            <div className="card-container">
            </div>
            <div className="description-container">
                <div className="form-container">
                    <UserForm />
                </div>
            </div>
        </div>
    )
}

UserForm.jsx

import React from 'react';

import Input from './Input';

export default function UserForm(props) {

    return (
        <div className="user-form">
            <form>
                <Input
                    placeholder="Nome a ser impresso" />
                <Input placeholder="E-mail" type="email" />
            </form>
        </div>
    )

}

Input.jsx

import React, { useState } from 'react';

import './Input.scss';

export default function Input(props) {
    const [inputVal, setInputVal] = useState('');

    function listenToInput(e) {
        setInputVal(e.target.value);
    }

    return (
        <div className="input-holder">
            <input
                type={props.type || 'text'}
                placeholder={props.placeholder}
                value={inputVal}
                onChange={listenToInput}/>
        </div>
    )
}
reactjs
2 Answers

Move

const [inputVal, setInputVal] = useState('');

To Home and pass inputVal and setInputVal all the way to Input as props.

This is called "prop drilling".

Halcyon0

Like @Gabriel Pichot said in comment: Refer to Lifting State Up

Use component's props to set input's value

if you need mutate state in your Home component, you can move your state from Input to Home. Then give the props to the UserForm, and give props again to Input

a example for how to do it: 

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/18.2.0/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/18.2.0/umd/react-dom.production.min.js"></script>
<script src="https://unpkg.com/babel-standalone@6/babel.min.js"></script>

    <div id="root"></div>

    <script type="text/babel">

        // const ThemeContext = React.createContext(themes.light);

        function Home() {
            const [inputVal, setInputVal] = React.useState('');
            const [inputVal2, setInputVal2] = React.useState('');

            return (
                <div className="home-container">
                    <div className="card-container">
                    </div>
                    <div className="description-container">
                        <div className="form-container">
                            <UserForm setInputVal={setInputVal} setInputVal2={setInputVal2} />
                        </div>
                    </div>
                    <p>first input: {inputVal}</p>
                    <p>second input: {inputVal2}</p>
                </div>
            )
        }

        function UserForm(props) {
            return (
                <div className="user-form">
                    <form>
                        <Input
                            placeholder="Nome a ser impresso" setInputVal={props.setInputVal} />
                        <Input placeholder="E-mail" type="email" setInputVal={props.setInputVal2} />
                    </form>
                </div>
            )
        }

        function Input(props) {
            function listenToInput(e) {
                props.setInputVal(e.target.value);
            }

            return (
                <div className="input-holder">
                    <input
                        type={props.type || 'text'}
                        placeholder={props.placeholder}
                        onChange={listenToInput} />
                </div>
            )
        }
    </script>

    <script type="text/babel">
        ReactDOM.render(
            <Home></Home>
            , document.getElementById("root"));
    </script>

Other ways (React.useContext)

Or you can use useContext, it can give your state and setState function to the grandchildren component

HsuTingHuan0
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