Dividing Float point numbers

The point that Nejc has tried to get at is that Javascript (for whatever reason) evaluates the expression 0.1 * 0.2 to be 0.020000000000000004. This is because of the way that Javascript maps decimal numbers. There are several ways around this:

• The easiest method is to truncate at the highest precision you think you'll need. If you're working with money, you only need precision to two decimal points so you could use:

    var a = 0.1;
    var b = 0.2;
    var c = a * b;
    //here is where the number is truncated and converted back into a number type
    if (Number(c.toFixed(2)) === 0.02) {
      //output here
    }

Note: toFixed(#) truncates the variable at the given # but also converts it into a string. In order to do a strict comparison, the two arguments must both be of the same type (in this case, numbers) regardless of the value inside the variable. You could do a == comparision without using the Numbers() conversion and the if-statement would evaluate to true. It's up to you.

• If you need more precision: You can truncate the expected answer to the amount of expected decimal points i.e. NumberOfDecimalPoints(x) + NumberOfDecimalPoints(y) = ExpectedNumberOfDecimalPoints when using multiplication. So, if we were to multiply 0.1 * 0.2, each has 1 decimal place so the expected number of decimal points in the answer is 2. So, you would use the Number(var.toFixed(#)) and # could be a variable conversion method to compare.
  

I hope that helps.

Do you mean multiplying floating point numbers in your title?

It looks to me like the expresson evaluates to true anyway and since both values are the same data type strict wouldn't have much effect, :-)