我想用HTML、CSS、Javascript、PHP和MySQL构建一个web。我希望我的网站有一个功能，客户希望从网站下载文件，如果他们不想下载得更快，不需要通过缩短链接，他们会输入代码，网站会使用PHP和MySQL来检查代码是否在数据库中。如果代码有效，他们将按下"下一步"按钮以下载文件。这是我的全部代码：
HTML+CSS+JS+PHP:
<!DOCTYPE html>
<html>
<head>
<title>HTML Document</title>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.5.2/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.16.0/umd/popper.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.5.2/js/bootstrap.min.js"></script>
<script>
function countWord() {
var x = document.getElementById("code").value;
if ((x.length)!=12) {
document.getElementById("ok").disabled = true;
} else if ((x.length)==12) {
document.getElementById("ok").disabled = false;
}
}
</script>
<style>
* {
padding:0;
margin:0;
box-sizing:border-box;
}
body {
background-color:#fff;
}
#code {
width:98%;
margin-left:1%;
}
#ok {
width:50%;
margin-left:25%;
margin-top:10px;
}
#nextbtn {
width:50%;
margin-left:25%;
margin-top:10px;
}
</style>
</head>
<body>
<form method="POST" name="code_form" id="code_form">
<input type="text" class="form-control" name="code" id="code" onkeyup="countWord();">
<input type="submit" name="ok" id="ok" class="btn btn-primary" disabled>
</form>
<button type="button" disabled class="btn btn-primary" id="nextbtn">Next</button>
<?php
$conn = mysqli_connect("","","","");
if (isset($_POST["ok"])) {
$code = $_POST["code"];
$sql = "SELECT * FROM code WHERE code='$code'";
$result = mysqli_query($conn,$sql);
if (mysqli_num_rows($result) == 1) {
echo "
<script>
var x = setTimeout(function(){
document.getElementById('nextbtn').disabled = false;
document.getElementById('nextbtn').onclick = function() {
window.open('https://www.youtube.com');
};
},0);
</script>
";
} else {
echo "<script>alert('Error');</script>";
}
}
?>
</body>
</html>
在下面的代码中，我希望能够在不使用setTimeout((函数的情况下立即运行该函数：
echo "
<script>
var x = setTimeout(function(){
document.getElementById('nextbtn').disabled = false;
document.getElementById('nextbtn').onclick = function() {
window.open('https://www.youtube.com');
};
},0);
</script>
";
请帮帮我！
此函数将立即被调用。IIFE
(function(){
document.getElementById('nextbtn').disabled = false;
document.getElementById('nextbtn').onclick = function() {
window.open('https://www.youtube.com');
})()
仅仅删除setTimeout还不够吗？
<script>
(function(){
document.getElementById('nextbtn').disabled = false;
document.getElementById('nextbtn').onclick = function() {
window.open('https://www.youtube.com');
})();
</script>
<script>
document.getElementById('nextbtn').disabled = false;
document.getElementById('nextbtn').onclick = function() {
window.open('https://www.youtube.com');
};
</script>
//---
<html>
<head>
<title>HTML Document</title>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.5.2/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.16.0/umd/popper.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.5.2/js/bootstrap.min.js"></script>
<script>
function countWord() {
var x = document.getElementById("code").value;
if ((x.length) != 12) {
document.getElementById("ok").disabled = true;
} else if ((x.length) == 12) {
document.getElementById("ok").disabled = false;
}
}
</script>
<style>
* {
padding:0;
margin:0;
box-sizing:border-box;
}
body {
background-color:#fff;
}
#code {
width:98%;
margin-left:1%;
}
#ok {
width:50%;
margin-left:25%;
margin-top:10px;
}
#nextbtn {
width:50%;
margin-left:25%;
margin-top:10px;
}
</style>
</head>
<body>
<form method="POST" name="code_form" id="code_form">
<input type="text" class="form-control" name="code" id="code" onkeyup="countWord();">
<input type="submit" name="ok" id="ok" class="btn btn-primary" disabled>
</form>
<button type="button" disabled class="btn btn-primary" id="nextbtn">Next</button>
<?php
//$conn = mysqli_connect("", "", "", "");
if (isset($_POST["ok"])) {
$code = $_POST["code"];
//$sql = "SELECT * FROM code WHERE code='$code'";
//$result = mysqli_query($conn, $sql);
//if (mysqli_num_rows($result) == 1) {
if (1 == 1) {
echo "<script>
document.getElementById('nextbtn').disabled = false;
document.getElementById('nextbtn').onclick = function() {
window.open('https://www.youtube.com');
};
</script>";
} else {
echo "<script>alert('Error');</script>";
}
}
?>
</body>