Question

I’m writing a small webpage that will enable students to answer questions and get feedback on their answers.

Part of this detection checks for common errors to give them guidance. Specifically I want to check if their answer is a power of ten out from the actual answer.

If the answer was 3.93E-6, this condition should activate if they type 3.93E2, 3.93E-9, 3.93 etc.

The obvious way to me to test this is to do something like this:

var correct = 3.93E-6; var entry = 3.93E-2; //really comes from an input box.  if (!(entry / correct)%10) {     alert ('power of ten error'); } 

However, this doesn’t work as error/correct doesn’t work for large/small numbers.

How can I fix this?

Live code at: http://bradshawenterprises.com/test.html

Answer 1

var num = 12.4123; var numString = num.toExponential() // numString = '1.24123e+1' 

This normalizes the number, but you have to parse it manually. (Like on how accurate the result has to be…)