To capture user input and perform form validation in React, we can utilize the built-in form handling capabilities and validation logic.

When a user interacts with a form, we can listen to the onSubmit event and execute a function to handle the form submission.

Here's an example of how we can handle form submission and perform basic validation:

1// Example form validation
2const validateForm = () => {
3  // Get form values
4  const name = document.getElementById('name').value;
5  const email = document.getElementById('email').value;
6  const password = document.getElementById('password').value;
7
8  // Perform validation
9  if (!name || !email || !password) {
10    console.log('Please fill in all fields');
11    return;
12  }
13
14  if (password.length < 6) {
15    console.log('Password must be at least 6 characters long');
16    return;
17  }
18
19  console.log('Form submitted successfully');
20};
21
22// Handle form submission
23const form = document.getElementById('form');
24form.addEventListener('submit', (e) => {
25  e.preventDefault();
26  validateForm();
27});

In the code snippet above, we define a function validateForm() that retrieves the values from the form inputs and performs the validation checks. If any field is empty or the password is less than 6 characters long, an error message is logged to the console.

We add an event listener to the form's submit event and prevent the default form submission behavior using e.preventDefault(). Instead, we call the validateForm() function to handle the form submission and perform the necessary validation.

This is a basic example, but in a real-world scenario, you would typically use a form library like React Hook Form or Formik to handle more complex form validation and management.

Next, we will explore implementing authentication in our payment app.

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// Example form validation

const validateForm = () => {

  // Get form values

  const name = document.getElementById('name').value;

  const email = document.getElementById('email').value;

  const password = document.getElementById('password').value;

​

  // Perform validation

  if (!name || !email || !password) {

    console.log('Please fill in all fields');

    return;

  }

​

  if (password.length < 6) {

    console.log('Password must be at least 6 characters long');

    return;

  }

​

  console.log('Form submitted successfully');

};

​

// Handle form submission

const form = document.getElementById('form');

form.addEventListener('submit', (e) => {

  e.preventDefault();

  validateForm();

});