Building a Vanilla JavaScript Calculator: Floating-Point Fixes and Input Handling

A developer shares progress from the foundations stage of learning vanilla JavaScript, describing a calculator project built as a capstone to the introduction module. The write-up outlines the core state variables used to track operands, operators, and flags that control display behavior after operator selection and evaluation. It highlights a custom rounding utility that scales numbers by powers of ten to avoid native floating-point errors such as 0.1 + 0.2. The author also describes a unified event pipeline for keyboard and mouse input, with a sanitizer for invalid decimals and operator overlaps, and an error handler that locks the interface on division by zero until reset.