无法在JavaScript中保留前导0。但是，您可以将此ID视为字符串并作为参数传递。
您可以尝试将以下代码设为字符串，以运行以下代码来保留前导0-
<html>
<head>
<script>
function sayHello(name, age, id) {
document.write (name + " is " + age + " years old, with id = "+id);
}
</script>
</head>
<body>
<p>Click the following button to call the function</p>
<form>
<input type="button" onclick="sayHello('John', 26, '0678')"
value="Display Employee Info">
</form>
</body>
</html>