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How can I check if a string is a float?

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清歌不尽
清歌不尽 2020-12-23 20:21

I am passing in a parameter called value. I\'d like to know if value is a float. So far, I have the following:

if (!isNaN(value))
{
    alert(\'this is a num
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14条回答
  • 旧时难觅i
    2020-12-23 20:23

    use this jquery code 

        <script>
    $(document).ready(function () {
        $(".allow_only_float").keypress(function (e) {

            if (e.which != 46 && e.which != 8 && e.which != 0 && (e.which < 48 || e.which > 57)) {
                e.preventDefault();//return false;
            }
            var avg = $('#<%=txtAverage.ClientID%>').val();
            var idx = avg.indexOf(".");
            if (idx > -1 && e.which == 46) {
                e.preventDefault();//return false;
            }
        });
    });
    </script>
<body>
    <input type='text' class='allow_only_float'>
</body>
    0 讨论(0)
  • 忘了有多久
    2020-12-23 20:26

    To check if a string is an integer or a float

    function isFloat(n) {
    return parseFloat(n.match(/^-?\d*(\.\d+)?$/))>0;
}

//alert(isFloat("3.444"));
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  • 你的背包
    2020-12-23 20:26

    This function returns the numeric value of a string regardless if int or float 

    function getNumericVal(str) {
    if(isNaN(str)) return;
    try {return parseFloat(str);} 
    catch(e) {return parseInt(str);}
}
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  • 生来不讨喜
    2020-12-23 20:28

    straight forward:

    if (parseFloat(value).toString() === value.toString()) {
    ...
}
    0 讨论(0)
  • 长情又很酷
    2020-12-23 20:30

    Following functions also check for format. E.g. JavaScript native parseInt and parseFloat functions also parse strings containing non numeric characters, and functions above have consequences of this.

    // For example, following code will work
var n = parseInt('123asd');
n == 123

    These functions will return false for such string.

    function isFloat(val) {
    var floatRegex = /^-?\d+(?:[.,]\d*?)?$/;
    if (!floatRegex.test(val))
        return false;

    val = parseFloat(val);
    if (isNaN(val))
        return false;
    return true;
}

function isInt(val) {
    var intRegex = /^-?\d+$/;
    if (!intRegex.test(val))
        return false;

    var intVal = parseInt(val, 10);
    return parseFloat(val) == intVal && !isNaN(intVal);
}
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  • 生来不讨喜
    2020-12-23 20:31 
    function checkFloat(value) {
    let parsed = Number.parseFloat(value);
    return (!Number.isNaN(parsed)) && (!Number.isInteger(parsed))
}
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