FrontendHaltJavaScript·Intermediate·Coding·1 min read
What problem does the module pattern solve?
Short interview answer
It creates a private, encapsulated scope for implementation details, exposing only a deliberately chosen public API. Consumers can't reach into or accidentally mutate internal state directly, which ES modules now provide natively at the file level.
Example
const counter = (() => { let count = 0; // private return { increment: () => ++count, value: () => count, };})();
counter.increment(); // 1counter.count; // undefinedKey takeaway
Explain the underlying mental model clearly, then support it with a concrete example and its trade-offs.