Need help with an assignment.

I am taking a HTML/JavaScript class and part of the assignment is killing me. I created the 4 function calculator and have all the validations correct except one. I need to validate if One or both input fields < -9999 or greater than 9999. I am told I need to convert the values to Integers, and then I will be able to test if the numbers are between -9999 and 9999. I caot figure out how to do this. Is there anyone that can help me out with this? I can post what I have so far if need be.