mathjs
An extensive math library for JavaScript and Node.js
...One of its defining features is its expression parser, which allows users to evaluate and manipulate mathematical expressions written in a natural math-like syntax. mathjs is highly modular, enabling developers to include only the functionality they need for optimized application size and performance. The project is widely used in scientific computing, educational software, calculators, engineering tools, and data analysis applications. Its architecture combines accessibility for beginners.