我正在使用 React 創建一個登錄頁面。即使輸入為空，Localhost:3000 仍會提示“感謝您注冊”。從教程中做到這一點并完全遵循代碼，但仍然無法弄清楚幾天。我嘗試洗掉 if-else 陳述句中雙引號之間的空格，但無濟于事。
這是代碼：
import { useState } from "react";
import styles from "./register.css";
import Login from "../../containers/login/index";
function Register({ props, history }) {
const [name, setName] = useState();
const [email, setEmail] = useState();
const [password, setPassword] = useState();
function registerClicked() {
if (name !== " " && email !== " " && password !== " ") {
console.log(name, email, password);
alert("Thanks for registering");
history.push("/");
} else {
alert("Please register to continue");
}
}
return(
<div className="regContainer">
<p className="registerTitle">Register to sign in</p>
<input type="text"
placeholder="Create username"
onChange={(nameText) => setName(nameText.target.value)} />
<input type="text"
placeholder="Email address"
onChange={(emailText) => setEmail(emailText.target.value)} />
<input type="password"
placeholder="Password"
onChange={(passwordText) => setPassword(passwordText.target.value)} />
<button onClick={() => registerClicked()}>Register</button>
<p className="loginInstead">Already have an account? Sign in instead</p>
</div>
);
}
export default Register;
uj5u.com熱心網友回復：
導致實際上const [name, setName] = useState();等于。nameundefined
設定一個默認值const [name, setName] = useState("");
或使用模糊判斷if(!name)
uj5u.com熱心網友回復：
注冊后的所有狀態都必須設定為null
if (name !== "" && email !== "" && password !== "") {
console.log(name, email, password);
alert("Thanks for registering");
setName(null);
setEmail(null);
setPassword(null);
history.push("/");
}
prop 值必須設定為所有輸入
<input type="text"
placeholder="Create username"
value={name}
onChange={(nameText) => setName(nameText.target.value)} />
<input type="text"
placeholder="Email address"
value={email}
onChange={(emailText) => setEmail(emailText.target.value)} />
<input type="password"
placeholder="Password"
value={password}
onChange={(passwordText) => setPassword(passwordText.target.value)} />
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標籤：javascript 反应 验证 警报