[英]JavaScript - “Identifier has already been declared”
在使用localStorage獲取注冊表/登錄表單以處理HTML時遇到問題。 作為我的任務的一部分,我不能使用數據庫或PHP,即使這些更容易。 特別是在我的提交功能期間發生了問題。
返回的語法錯誤是“已聲明標識符registerUser”,並在控制台中突出顯示const reponse = processUser (username.value, password.value)
。
這是我的JavaScript代碼:
//setup form
window.addEventListener("DOMContentLoaded", setupForm);
function setupForm() {
const form = document.getElementById("login");
form.addEventListener("submit", handleSubmit);
}
//handle Submit
function handleSubmit(event) {
event.preventDefault();
const {
Username,
Password,
login_type,
result
} = event.target;
const processUser = login_type.value == "register" ? registerUser : loginUser;
const response = processUser(username.value, password.value);
result.innerHTML = response;
}
//register new user
function registerUser(username, password) {
window.localStorage.setItem("username", username);
window.localStorage.setItem("password", password);
return 'New user ${username} now registered!';
}
//login existing user
function loginUser(username, password) {
const registeredUser = window.localStorage.getItem("username", username);
const registeredUser = window.localStorage.getItem("password", password);
const validUser = username == registeredUser;
const validPassword = password == registeredUser;
if (validUser && validPassword) {
return 'User ${username} successfully logged-in!';
}
//error form for incorrect username or password
else if (!validUser) return 'Incorrect username or password';
}
HTML表單:
<fieldset>
<form id="login" action="submit" method="post">
<legend><b>Login here!</b></legend><br />
<div>
<label for="username">Username:</label>
<input id="username" type="text" name="username" required />
</div>
<div>
<label for="password">Password:</label>
<input id="password" type="password" name="Password" required />
</div>
</fieldset>
<span>
<input id="login" type="hidden" name="login_type" value="login" checked="checked"></input>
<!--Hidden for the purposes of my script working-->
<input type="submit" value="Submit" /><br /><br />
<output name="result"></output>
</fieldset>
</span>
任何幫助將不勝感激,因為這非常令人沮喪!
2個變量具有已registeredUser
的同名用戶。
const registeredUser = window.localStorage.getItem("username",
username);
const registeredUser = window.localStorage.getItem("password",
password);
因此,我沒有嘗試使用registeredUser
,而是將其更改為registeredPassword
//login existing user
function loginUser(username, password){
const registeredUser = window.localStorage.getItem("username",
username);
const registeredPassword = window.localStorage.getItem("password",
password);
const validUser = username === registeredUser;
const validPassword = password === registeredPassword;
也使用===
而不是==
原因
你宣布了兩次標識符:
const registeredUser = window.localStorage.getItem("username",
username);
const registeredUser = window.localStorage.getItem("password",
password);
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