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Grokking Node.js Design Patterns for Interviews

Solution: Auto-Default Missing Values

Explore how to use the Proxy design pattern to intercept object property accesses in Node.js. Learn to safely return default values for missing configuration keys without altering the original object, preventing runtime errors and ensuring predictable behavior in your applications.

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Solution explanation

  • Lines 2–5: We define the base config object with only two properties: appName and version.

    • This represents a partial configuration that may be missing keys.

    • The Proxy will fill those gaps dynamically without mutating this object.

  • Lines 8–15: We create a new Proxy that intercepts property reads through the get() trap.

    • When a property exists in the ...