Egal.js provides a strict equality test function (`egal`) for JavaScript that handles both built-in and custom value objects (those with a `valueOf` function), allowing semantic comparison of objects like `Date` and `RegExp` beyond simple reference equality. It also includes a `deepEgal` function for recursive comparison of plain objects and arrays while maintaining type safety and handling circular references. This library is designed for JavaScript developers who need precise, type-safe equality testing beyond the limitations of the standard `===` operator.