4. Objects and Prototypes

Objects are JavaScript’s fundamental data structure. Intuitively, an object represents a table relating strings to values. But when you dig deeper, there is a fair amount of machinery that goes into objects.

Like many object-oriented languages, JavaScript provides support for implementation inheritance: the reuse of code or data through a dynamic delegation mechanism. But unlike many conventional languages, JavaScript’s inheritance mechanism is based on prototypes rather than classes. For many programmers, JavaScript is the first object-oriented language they encounter without classes.

In many languages, every object is an instance of an associated class, which provides code shared between all its instances. JavaScript, ...

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