Javascript 无限循环提示
[英]Javascript infinite loop in prompt
问题描述
So i have just made a simple HTML page in which a JS script runs when the page loads.
所以我刚刚制作了一个简单的 HTML 页面，其中在页面加载时运行 JS 脚本。 But the problem is that it just goes infinite after asking password.但问题是在询问密码后它会变得无限。 I tried to find some solutions but failed to do the same.我试图找到一些解决方案，但未能如愿以偿。 Please help.请帮忙。 Below is the code.下面是代码。
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Alert test</title>
</head>
<body onload="alert()">
<script>
function alert() {
var uname, pass, corr_uname = "admin", corr_pass = "admin";
while(!uname) {
uname = prompt("Enter Username: ");
}
while(!pass) {
pass = prompt("Enter Password: ");
}
if((uname == corr_uname) && (pass == corr_pass)) {
alert("Access Granted!!");
} else {
alert("Access Denied!");
alert();
}
}
</script>
<h1>Welcome!</h1>
</body>
</html>
The funny thing is that when i run the same code (JS runs after clicking a button) in W3Schools, it just works fine!!有趣的是，当我在 W3Schools 中运行相同的代码（JS 在单击按钮后运行）时，它工作正常！
2 个解决方案
解决方案1
3 已采纳 2022-05-03 18:29:19
The problem is that you have created a function named alert which already exists in javascript, so you are calling it recursively and infinitely.问题是您已经创建了一个名为 function 的alert ，它已经存在于 javascript 中，因此您正在递归和无限地调用它。
Solution fix解决方案修复
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Alert test</title>
</head>
<body onload="alert2()">
<script>
function alert2() {
var uname, pass, corr_uname = "admin", corr_pass = "admin";
while(!uname) {
uname = prompt("Enter Username: ");
}
while(!pass) {
pass = prompt("Enter Password: ");
}
if((uname == corr_uname) && (pass == corr_pass)) {
alert("Access Granted!!");
} else {
alert("Access Denied!");
myFunction();
}
}
</script>
<h1>Welcome!</h1>
</body>
</html>
I renamed your functional alert to alert2 .我将您的功能alert重命名为alert2 。
Kindly accept it as answer if it works for you, thanks!如果对您有用，请采纳为答案，谢谢！
解决方案2
1 2022-05-03 19:03:54
JavaScript had mutable built-in functions so your alert function overwrites the native alert and every alert call becomes recursive in a never ending loop. JavaScript 具有可变的内置函数，因此您的alert function 会覆盖本机警报，并且每个警报调用都会在永无止境的循环中递归。
Besides renaming the function, there's no need to use a while loop since prompt stalls execution.除了重命名 function 之外，不需要使用 while 循环，因为提示会停止执行。 You can use uname && to invalidate the username if the user cancels the username prompt.如果用户取消用户名提示，您可以使用uname &&使用户名无效。
There's also no need to use <body onload="??"> if you just put the script within <head>...</head>如果您只是将脚本放在<head>...</head>中，也无需使用<body onload="??"> >
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Alert test</title>
<script>
const corr_uname = "admin", corr_pass = "admin";
function authenticate() {
const uname = prompt("Enter Username: ");
const pass = uname && prompt("Enter Password: ");
const isCredentialsValid = uname == corr_uname && (pass == corr_pass);
const accessType = isCredentialsValid ? 'Granted' : 'Denied';
alert(`Access ${accessType}!!`);
}
authenticate();
</script>
</head>
<body>
<h1>Welcome!</h1>
</body>
</html>
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