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(.0) float in Javascript

I am trying to do write a code for a function that displays a boolean after checking if the value is an integer or not. see my definition of an integer in my ideal outputs below when i call the function:

So far, my code is failing because it generates true for validInteger ( 10.0 ) when i want it to be false. Javascript is struggling because 10.0 = 10

DESIRED OUTPUT

validInteger ( '10' ) // should return True
validInteger ( 10 ) // should return True 
validInteger ( '-10' ) // should return False
validInteger ( -10 ) // should return False
validInteger ( 0.0 ) // should return False
validInteger ( 10.0 ) // should return False
validInteger ( -10.0 ) // should return False

I wonder if anyone has an idea on how i can get a false result for validInteger ( 10.0 ). so far this is the code i have been able to write:

function validInteger (value) { // value can be a string or a number (integer)
  
  const numberValue = Number(value);
  return Number.isInteger(numberValue) && numberValue >= 0 && String(numberValue) ===     String(value);

}
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2

Answers


  1. 0

    10 and 10.0 are the same in JS. It’s a primitive value of type number. You cannot distinguish between these notations in runtume.

    The JavaScript Number type is a double-precision 64-bit binary format IEEE 754 value

    https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number

    You can check only whether an expression is a number and has a decimal part with Number.isInteger().

    Also it seems as a XY problem since its purpose isn’t clear.

    For allocating integers you could examine typed arrays.

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  2. 0

    The solution I see here is to make the function receive the argument as a string.

    Something like this.

    function validIntegerString(value) { // value must be a string
  return (
    value.length != 0 && !value.includes(".") && Number.isInteger(Number(value))
  );
}
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