React Forms - Checkbox
Checkbox
For checkboxes, use the checked attribute
instead of value to control its state.
We'll use the useState Hook to manage the value of the textarea:
In the handleChange function,
use the e.target.type property check if the current input is a checkbox or not.
Example:
React uses the checked attribute to control the checkbox:
import { useState } from 'react';
import { createRoot } from 'react-dom/client';
function MyForm() {
const [inputs, setInputs] = useState({});
const handleChange = (e) => {
const target = e.target;
const value = target.type === 'checkbox' ? target.checked : target.value;
const name = target.name;
setInputs(values => ({...values, [name]: value}))
}
const handleSubmit = (event) => {
let fillings = '';
if (inputs.tomato) fillings += 'tomato';
if (inputs.onion) {
if (inputs.tomato) fillings += ' and ';
fillings += 'onion';
}
if (fillings == '') fillings = 'no fillings';
alert(`${inputs.firstname} wants a burger with ${fillings}`);
event.preventDefault();
};
return (
<form onSubmit={handleSubmit}>
<label>My name is:
<input
type="text"
name="firstname"
value={inputs.firstname}
onChange={handleChange}
/>
</label>
<p>I want a burger with:</p>
<label>Tomato:
<input
type="checkbox"
name="tomato"
checked={inputs.tomato}
onChange={handleChange}
/>
</label>
<label>Onion:
<input
type="checkbox"
name="onion"
checked={inputs.onion}
onChange={handleChange}
/>
</label>
<button type="submit">Submit
</form>
)
}
createRoot(document.getElementById('root')).render(
<MyForm />
);Initial Values
To add initial values to the input fields in the example above,
add the proper keys and values to the useState object:
Example:
Use initial values for the input fields:
function MyForm() {
const [inputs, setInputs] = useState({
firstname: 'John',
tomato: true,
onion: false
});
...