Flash cards
Review the key moves
What is the main idea behind React Forms - Checkbox?
Lesson checks
Practice each idea before moving on
Short Mimo-style checks built from this lesson's code, terms, and sequence.
Which statement best captures the main point of this lesson?
Complete the missing token from the example code.
___ { useState } from 'react';Put the learning moves in the order that makes the concept easiest to apply.
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
});
...