React表單處理指南：如何處理複雜的前端表單校驗

import React, { Component } from 'react';

class Form extends Component {
  constructor(props) {
    super(props);
    this.state = {
      username: '',
      password: '',
      confirmPassword: '',
      errors: {
        username: '',
        password: '',
        confirmPassword: ''
      }
    };
  }

  handleInputChange = (event) => {
    const { name, value } = event.target;
    this.setState({
      [name]: value
    });
  };

  validateForm = () => {
    const { username, password, confirmPassword } = this.state;
    let errors = {};

    if (!username) {
      errors.username = '用户名不能为空';
    }

    if (!password) {
      errors.password = '密码不能为空';
    } else if (password.length < 6) {
      errors.password = '密码长度必须大于6位';
    }

    if (confirmPassword !== password) {
      errors.confirmPassword = '两次密码输入不一致';
    }

    this.setState({ errors });

    return Object.keys(errors).length === 0;
  };

  handleSubmit = (event) => {
    event.preventDefault();
    if (this.validateForm()) {
      // 表单验证通过，提交表单
      console.log('提交表单');
    }
  };

  render() {
    const { username, password, confirmPassword, errors } = this.state;

    return (
      <form onSubmit={this.handleSubmit}>
        <div>
          <label>用户名：</label>
          <input
            type="text"
            name="username"
            value={username}
            onChange={this.handleInputChange}
          />
          {errors.username && <span>{errors.username}</span>}
        </div>

        <div>
          <label>密码：</label>
          <input
            type="password"
            name="password"
            value={password}
            onChange={this.handleInputChange}
          />
          {errors.password && <span>{errors.password}</span>}
        </div>

        <div>
          <label>确认密码：</label>
          <input
            type="password"
            name="confirmPassword"
            value={confirmPassword}
            onChange={this.handleInputChange}
          />
          {errors.confirmPassword && <span>{errors.confirmPassword}</span>}
        </div>

        <button type="submit">提交</button>
      </form>
    );
  }
}

export default Form;

import React from 'react';
import { useFormik } from 'formik';
import * as Yup from 'yup';

const Form = () => {
  const formik = useFormik({
    initialValues: {
      email: '',
      password: ''
    },
    validationSchema: Yup.object({
      email: Yup.string().email('无效的邮箱地址').required('邮箱不能为空'),
      password: Yup.string()
        .min(6, '密码长度必须大于6位')
        .required('密码不能为空')
    }),
    onSubmit: (values) => {
      console.log(values);
    }
  });

  return (
    <form onSubmit={formik.handleSubmit}>
      <div>
        <label htmlFor="email">邮箱：</label>
        <input
          id="email"
          type="email"
          {...formik.getFieldProps('email')}
        />
        {formik.touched.email && formik.errors.email && (
          <div>{formik.errors.email}</div>
        )}
      </div>

      <div>
        <label htmlFor="password">密码：</label>
        <input
          id="password"
          type="password"
          {...formik.getFieldProps('password')}
        />
        {formik.touched.password && formik.errors.password && (
          <div>{formik.errors.password}</div>
        )}
      </div>

      <button type="submit">提交</button>
    </form>
  );
};

export default Form;