The Javascript Prototype

The definition of a Prototype

All objects in JavaScript inherit from at least one other object. The object being inherited from is known as the prototype, and the inherited properties can be found in the prototype object of the constructor.

The post Understanding Prototype says

JavaScript objects also have one additional attribute: a pointer to another object. We call this pointer the object’s prototype. If you try to look up a key on an object and it is not found, JavaScript will look for it in the prototype.

plain english guide to javascript prototypes :

Prototype chains (aka prototype inheritance) Every object in Javascript has a prototype. When a messages reaches an object, JavaScript will attempt to find a property in that object first, if it cannot find it then the message will be sent to the object’s prototype and so on. This works just like single parent inheritance in a class based language.

The Prototype chain - more

Each object has an internal property called prototype, which links to another object. The prototype object has a prototype object of its own, and so on – this is referred to as the prototype chain. If you follow an object’s prototype chain, you will eventually reach the core Object prototype whose prototype is null, signalling the end of the chain.

A use case of the prototype.