JavaScript Type Coercion: Silent Bugs and How to Avoid Them

The article explains how JavaScript silently converts value types when an operator expects a different type, producing wrong results without raising errors. It outlines the core rule for the + operator, which concatenates if either operand is a string and otherwise adds numbers, along with examples like "5" + 3 and [] + {}. It describes how loose equality (==) applies a conversion table that is hard to predict, recommending the strict equality operator (===) which never converts types. Practical risks include form input strings being concatenated, API numeric values arriving as strings, and falsy checks skipping valid zero values. The author recommends converting values explicitly at the boundary of code using Number() or String() and checking types with typeof.