The answer
Use === and !== instead of == and !=. Convert types explicitly with Number() and String(). Validate inputs at function boundaries. Use TypeScript for large codebases and strict mode to catch silent bugs.
JavaScript as a Loosely Typed Language Explained
How do you avoid type coercion bugs in JavaScript?
More FAQs in JavaScript as a Loosely Typed Language Explained
Variables can hold any type and change types at runtime. You never declare a variable's type. The engine coerces values automatically when types do not match in operations.
Because the + operator favors string concatenation. When one operand is a string, the other is coerced to a string. So 1 becomes '1' and the result is '12'.
Dynamically and weakly (loosely) typed. Types are checked at runtime, not compile time. Variables can hold any type and the engine coerces values automatically.
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