javascriptdivide-by-zero

Best way to prevent/handle divide by 0 in javascript


What is the best way to prevent divide by 0 in javascript that is accepting user inputs. If there is no particular way to achieve this what would be the best way to handle such a situation so as to not prevent other scripts from executing?

Any insights are much appreciated.


Solution

  • There is no way to do that with the normal / and /= operators.

    The best way to do what you want is with guards:

    function notZero(n) {
      n = +n;  // Coerce to number.
      if (!n) {  // Matches +0, -0, NaN
        throw new Error('Invalid dividend ' + n);
      }
      return n;
    }
    

    and then do division like

    numerator / notZero(denominator)
    

    Alternatively you can always guard the output

    function dividend(numerator, denominator) {
      var quotient = numerator / denominator;
      if (quotient !== quotient) { throw new Error(numerator + " / " + denominator); }
      return quotient;
    }
    

    but that loses the readability and expressiveness of /=.