floating point - Javascript float subtract

Question

I was wondering how can I subtract two negative Floating-Point numbers in javascript. I tried:

alert(-0.2-0.1);

and the result is -0.30000000000000004. Am I doing something wrong? What do I have to do to get -0.3 ?

Answer 1

No, nothing wrong with your code, most decimal fractions cannot be represented exactly in binary, use

number.toFixed(x)

Where x is the number of decimals you want and number is the result of the subtraction.