How to create a calculator application with JavaScript

I am wondering if there is a way to create a calculator with javascript for linear algebra.
I would like to create calculators similar to Emathhelp.net’s calculators. How hard would it be to create an online calculator app, possibly with step by step solutions.

There’s nothing preventing you from using JavaScript to build this tool. It might be more difficult than it would be in a language that has better math libraries, but it can be done. The example that you linked to may very well be written in JavaScript.