出于某种原因,默认值总是显示出来,而最后输入的值却没有显示出来。
APP.JS
import React, { useState } from 'react';
import User from './Components/User';
import Card from './Components/Card';
function App() {
const [user, setUser] = useState([{username: "Alex", age: 11}]);
const handleUserAdd = (user1) => {
setUser(prevState => ([
...prevState, user1
]));
console.log(user);
}
return (
<div className="App">
<Card>
<User onUserAdd={handleUserAdd}/>
</Card>
</div>
);
}
export default App;
USER.JS
import React, { useState } from 'react';
const User = (props) => {
const [name, setName] = useState("");
const [years, setYears] = useState(0);
const handleOnNameChange = (e) => {
setName(e.target.value);
}
const handleOnAgeChange = (e) => {
setYears(e.target.value);
}
const handleOnSubmit = (e) =>{
e.preventDefault();
//if(years !== 0){
const user = {
username: name,
age: years
};
props.onUserAdd(user);
//}
setName("");
setYears(0);
}
return (
<>
<form onSubmit={handleOnSubmit}>
<div className="mb-3">
<label htmlFor="exampleInputEmail1" className="form-label">Username:</label>
<input className="form-control" aria-describedby="emailHelp" value={name} onChange={handleOnNameChange} />
</div>
<div className="mb-3">
<label htmlFor="exampleInputPassword1" className="form-label">Age:</label>
<input type="number" min={1} max={120} className="form-control" value={years} onChange={handleOnAgeChange} />
</div>
<button type="submit" className="btn btn-primary">Add User</button>
</form>
</>
);
}
export default User;
它显示 Alex 11,这是默认值,如果我将其设置为空,它将显示为空项目。 在输入上,我输入了 3 个值:值 1、1;值 2,2;值 3,3。值 3,3 未显示,如果我输入 Value4,4,则值 3 将显示,而值 4,4 不会显示。我不明白为什么它用默认值填充第一个值而不是将其更改为 Value1,1。为什么不显示最后一个?
如果您能帮助我,我将不胜感激。