checkValidity第一个只是重命名你的函数。瞧。
第二个是这样的：避免通过内联属性赋值来处理事件，而使用
addEventListenerconst pass = '2207'
const button = Array.from(document.getElementsByTagName("button"))[0];
button.addEventListener("click", checkValidity);
function checkValidity() {
const pass_code = document.getElementById("passcode").value;
if (pass_code == pass){
alert("Correct Passcode!");
}
else{
alert("Wrong Passcode!");
}
}<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Login</title>
</head>
<body style="background-color: rgb(0, 255, 195); text-align: center">
<div id="display">
<p style="color:black">Enter your Passcode:</p>
<input id="passcode" type = "password">
<button>Enter↵</button>
</div>
<script src = "script.js"></script>
</body>
</html>P.S. 还要避免内联样式，而使用内部/外部CSS。