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How do I check that a number is float or integer?

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栀梦
栀梦 2020-11-22 00:01

How to find that a number is float or integer?

1.25 --> float  
1 --> integer  
0 --> integer  
0.25 --> float
<
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  • 南旧
    2020-11-22 00:29

    It really doesn't have to be so complicated. The numeric value of an integer's parseFloat() and parseInt() equivalents will be the same. Thus you can do like so:

    function isInt(value){ 
    return (parseFloat(value) == parseInt(value)) && !isNaN(value);
}

    Then

    if (isInt(x)) // do work

    This will also allow for string checks and thus is not strict. If want a strong type solution (aka, wont work with strings):

    function is_int(value){ return !isNaN(parseInt(value * 1) }
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  • 慢半拍i
    2020-11-22 00:31

    You can use a simple regular expression:

    function isInt(value) {

    var er = /^-?[0-9]+$/;

    return er.test(value);
}

    Or you can use the below functions too, according your needs. They are developed by the PHPJS Project.

    is_int() => Check if variable type is integer and if its content is integer

    is_float() => Check if variable type is float and if its content is float

    ctype_digit() => Check if variable type is string and if its content has only decimal digits

    Update 1

    Now it checks negative numbers too, thanks for @ChrisBartley comment!

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  • 遇见更好的自我
    2020-11-22 00:32

    This solution worked for me.

    <html>
<body>
  <form method="post" action="#">
    <input type="text" id="number_id"/>
    <input type="submit" value="send"/>
  </form>
  <p id="message"></p>
  <script>
    var flt=document.getElementById("number_id").value;
    if(isNaN(flt)==false && Number.isInteger(flt)==false)
    {
     document.getElementById("message").innerHTML="the number_id is a float ";
    }
   else 
   {
     document.getElementById("message").innerHTML="the number_id is a Integer";
   }
  </script>
</body>
</html>
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  • 滥情空心
    2020-11-22 00:32

    Condtion for floating validation :

    if (lnk.value == +lnk.value && lnk.value != (lnk.value | 0))

    Condtion for Integer validation :

    if (lnk.value == +lnk.value && lnk.value == (lnk.value | 0))

    Hope this might be helpful.

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  • 南笙
    2020-11-22 00:33

    How about this one?

    isFloat(num) {
    return typeof num === "number" && !Number.isInteger(num);
}
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  • 盖世英雄少女心
    2020-11-22 00:33

    Any Float number with a zero decimal part (e.g. 1.0, 12.00, 0.0) are implicitly cast to Integer, so it is not possible to check if they are Float or not.

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