JavaScript for simple JS calculator Once you have all these files saved in the same folder, it’s time to test out your work. Here's the script for scientific calculator. The prerequisites Every C program has at least one function, which is main(), and all the most trivial programs can define additional functions. We need to create a basic structure using HTML, style it using CSS and make it work using JavaScript, which works on browser. I've made some improvements to it before posting this. It should perform operation according to the operator entered and must take input in given format. The app.js file contains the logic behind the calculator. Here we’ve only scratched the surface of all the string functions JavaScript can do and it is constantly evolving. In this article, we will build a simple calculator using JavaScript that can carry out basic arithmetic operations. First, we need to figure out how many buttons we are going to need. For now, we stick to the minimum viable functionalities for our basic calculator. Basically I just wrote this calculator as a sort of JavaScript test for myself. View Answers. 1. How to Make a Simple Calculator in Java: After the "Hello World!" Javascript Code: