代码示例：（标识：js_validation_check）
<!DOCTYPE html>
<html>
<body>
<h1>JavaScript 验证</h1>
<p>请输入一个数字然后点击 OK：</p>
<input id="id1" type="number" min="100" max="300" required>
<button onclick="myFunction()">OK</button>
<p>如果数字小于 100 或大于 300，将显示错误消息。</p>
<p id="demo"></p>
<script>
function myFunction() {
const inpObj = document.getElementById("id1");
if (!inpObj.checkValidity()) {
document.getElementById("demo").innerHTML = inpObj.validationMessage;
} else {
document.getElementById("demo").innerHTML = "Input OK";
}
}
</script>
</body>
</html>
