this project is one of freecodecamp front-end program advanced projects which tests javascript skills and ability to find solutions when the programmer faces obstacles. In this project I used vanilla javascript as a challenge and no use of any library.
This function saved alot of time. It calculates a string and return the results.
e.g : var x = "5+5"
eval(x) // returns 10
index.html - the main structure of the calculator
style.css - main stylesheet for the project.
script.js - main script for calculating user input.