吴裕雄--天生自然 JAVASCRIPT开发学习: 验证 API

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
</head>
<body>

<p>输入数字并点击验证按钮:</p>

<input id="id1" type="number" min="100" max="300" required>
<button onclick="myFunction()">验证</button>

<p>如果输入的数字小于 100 或大于300,会提示错误信息。</p>

<p id="demo"></p>

<script>
function myFunction() {
    var inpObj = document.getElementById("id1");
    if (inpObj.checkValidity() == false) {
        document.getElementById("demo").innerHTML = inpObj.validationMessage;
    } else {
        document.getElementById("demo").innerHTML = "输入正确";
    }
}
</script>

</body>
</html>

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
</head>
<body>

<p>输入数字并点击验证按钮:</p>

<input id="id1" type="number" max="100">
<button onclick="myFunction()">验证</button>

<p>如果输入的数字大于 100 ( input 的 max 属性), 会显示错误信息。</p>

<p id="demo"></p>

<script>
function myFunction() {
    var txt = "";
    if (document.getElementById("id1").validity.rangeOverflow) {
        txt = "输入的值太大了";
    } else {
        txt = "输入正确";
    }
    document.getElementById("demo").innerHTML = txt;
}
</script>

</body>
</html>

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
</head>
<body>

<p>输入数字并点击验证按钮:</p>
<input id="id1" type="number" min="100" required>
<button onclick="myFunction()">验证</button>

<p>如果输入的数字小于 100 ( input 的 min 属性), 会显示错误信息。</p>

<p id="demo"></p>

<script>
function myFunction() {
    var txt = "";
    var inpObj = document.getElementById("id1");
    if(!isNumeric(inpObj.value)) {
        txt = "你输入的不是数字";
    } else if (inpObj.validity.rangeUnderflow) {
        txt = "输入的值太小了";
    } else {
        txt = "输入正确";
    }
    document.getElementById("demo").innerHTML = txt;
}

// 判断输入是否为数字
function isNumeric(n) {
    return !isNaN(parseFloat(n)) && isFinite(n);
}
</script>

</body>
</html>

原文地址:https://www.cnblogs.com/tszr/p/10942896.html