How to ensure javascript addition instead of string concatenation (Not always adding integers)

Question

Through my javascript library, I end up with a string that represents a number. Now I want to preform an addition on that number without it doing a string concatenation inst

Answer 1

I'm going to assume that float addition is sufficient, and if it isn't, then you'll need to dig deeper.

function alwaysAddAsNumbers(numberOne, numberTwo){
  var parseOne = parseFloat(numberOne),
      parseTwo = parseFloat(numberTwo);
  if (isNaN(parseOne)) parseOne = 0;
  if (isNaN(parseTwo)) parseTwo = 0;
  return parseOne + parseTwo;
}

To take what @Asad said, you might want to do this instead:

function alwaysAddAsNumbers(a, b){
  var m = 0,
      n = 0,
      d = /\./,
      f = parseFloat,
      i = parseInt,
      t = isNaN,
      r = 10;
  m = (d.test(a)) ? f(a) : i(a,r);
  n = (d.test(b)) ? f(b) : i(b,r);
  if (t(m)) m = 0;
  if (t(n)) n = 0;
  return m + n;
}

this will always give you at least a zero output, and doesn't tell you if either one is NaN.