Prototype

Summary

The underlying mechanism by which JavaScript objects inherit properties and methods from other objects — classes are just a friendlier syntax over this. Prototype chains are part of normal property lookup, so understanding them makes built-in objects, classes, inheritance, and method resolution much less mysterious.

• 1Log `Object.getPrototypeOf()` on an array or object to see its prototype chain. Validate your understanding by applying it in a small practical example.
• 2Add a method to `Array.prototype` as an exercise (not production practice). Test the result on both a successful path and an invalid or unexpected input.
• 3Learn how property lookup walks the prototype chain when a property isn't found directly.