有时会遇到多个位置需要用户输入的情况，若每个状态都配置state或handler会很繁琐，可以尝试下面的方法
import * as React from 'react';
const LoginForm = () => {
// 将多个状态合并为对象
const [state, setState] = React.useState({
email: '',
password: '',
});
// 通过单个handler统一管理
const handleChange = (e) => {
setState({
...state,
[e.target.id]: e.target.value,
});
};
const handleSubmit = (e) => {
e.preventDefault();
alert(state.email + ' ' + state.password);
};
return (
<form onSubmit={handleSubmit}>
<div>
<label htmlFor="email">Email</label>
<input
id="email"
type="text"
value={state.email}
onChange={handleChange}
/>
</div>
<div>
<label htmlFor="password">Password</label>
<input
id="password"
type="password"
value={state.password}
onChange={handleChange}
/>
</div>
<button type="submit">Submit</button>
</form>
);
};
export { LoginForm };
由于每次用户输入后都需要数据重置回初始状态，可以使用以下方法来预设初始值，并重置Form内容，方便新用户的再次输入
import * as React from 'react';
const LoginForm = () => {
// 初始
const [state, setState] = React.useState({
// 设置初始值
email: '123@456.com',
password: '12345',
});
const handleChange = (e) => {
setState({
...state,
[e.target.id]: e.target.value,
});
};
const handleSubmit = (e) => {
e.preventDefault();
// 在这里重置状态
setState({
email: '',
password: '',
});
alert(state.email + ' ' + state.password);
};
return (
<form onSubmit={handleSubmit}>
<div>
<label htmlFor="email">Email</label>
<input
id="email"
type="text"
value={state.email}
onChange={handleChange}
/>
</div>
<div>
<label htmlFor="password">Password</label>
<input
id="password"
type="password"
value={state.password}
onChange={handleChange}
/>
</div>
<button type="submit">Submit</button>
</form>
);
};
export { LoginForm };
屏幕显示如下，submit后 Form内容会被重置
也可以考虑设置一个变量来统一管理初始值，方便对状态的查找和维护
import * as React from 'react';
const LoginForm = () => {
// 定义初始值
const INITIAL_STATE = {
email: '',
password: '',
};
const [state, setState] = React.useState(INITIAL_STATE);
const handleChange = (e) => {
setState({
...state,
[e.target.id]: e.target.value,
});
};
const handleSubmit = (e) => {
e.preventDefault();
// 重置初始值
setState(INITIAL_STATE);
};
return (
<form onSubmit={handleSubmit}>
<div>
<label htmlFor="email">Email</label>
<input
id="email"
type="text"
value={state.email}
onChange={handleChange}
/>
</div>
<div>
<label htmlFor="password">Password</label>
<input
id="password"
type="password"
value={state.password}
onChange={handleChange}
/>
</div>
<button type="submit">Submit</button>
</form>
);
};
export { LoginForm };
验证Form的输入是不可或缺的流程，可参考以下方案
import * as React from 'react';
const LoginForm = () => {
const INITIAL_STATE = {
email: '',
password: '',
};
// 设置Validation要求
const VALIDATION = {
email: [
{
isValid: (value) => !!value,
message: 'Is required.',
},
{
isValid: (value) => /\S+@\S+\.\S+/.test(value),
message: 'Needs to be an email.',
},
],
password: [
{
isValid: (value) => !!value,
message: 'Is required.',
},
],
};
// 获取ErrorsFields
const getErrorState = (state) =>
Object.keys(state).reduce((acc, key) => {
if (!VALIDATION[key]) return acc;
const errorsPerField = VALIDATION[key].map((validation) => ({
isValid: validation.isValid(state[key]),
message: validation.message,
})).filter((errorPerField) => !errorPerField.isValid);
return { ...acc, [key]: errorsPerField };
}, {});
const [state, setState] = React.useState(INITIAL_STATE);
// 设置错误信息变量
const errorState = getErrorState(state);
console.log(errorState);
const handleChange = (e) => {
setState({
...state,
[e.target.id]: e.target.value,
});
};
const handleSubmit = (e) => {
e.preventDefault();
// 获取错误反馈
const hasErrors = Object.values(errorFields).flat().length > 0;
if (hasErrors) return;
setState(INITIAL_STATE);
};
return (
<form onSubmit={handleSubmit}>
<div>
<label htmlFor="email">Email</label>
<input
id="email"
type="text"
value={state.email}
onChange={handleChange}
/>
{/* 显示email错误 */}
{errorState.email?.length ? (
<span style={{ color: 'red' }}>
{errorState.email[0].message}
</span>
) : null}
</div>
<div>
<label htmlFor="password">Password</label>
<input
id="password"
type="password"
value={state.password}
onChange={handleChange}
/>
{/* 显示password错误 */}
{errorState.password?.length ? (
<span style={{ color: 'red' }}>
{errorState.password[0].message}
</span>
) : null}
</div>
<button type="submit">Submit</button>
</form>
);
};
export { LoginForm };
效果显示如下
到这里完成一个简易的React Login Form， 然而现实中React Form的问题还有很多， 随着学习的深入，会继续探索Form实用的复杂性，更多关于React特征Form数据管理的资料请关注其它相关文章！
