JS判断输入框值是否为空

时间：2023-11-24 09:43:02
<!DOCTYPE html>

<html>

<head lang="en">

    <meta charset="UTF-8">

    <title>JS判断输入框的值是否为空</title>

</head>

<body>

<input type="text" id="txt"/>

<input type="button" value="检测" id="btn">

<script>

    var oTxt = document.getElementById('txt');

    var oBtn = document.getElementById('btn');

    function isnull(val) {

        var str = val.replace(/(^\s*)|(\s*$)/g, '');//去除空格;

        if (str == '' || str == undefined || str == null) {

            //return true;

            console.log('空')

        } else {

            //return false;

            console.log('非空');

        }

    }

    oBtn.onclick = function () {

        isnull( oTxt.value );

    }

</script>

</body>

</html>

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