What does EventEmitter.call() do?

Question

I saw this code sample:

function Dog(name) {     this.name = name;     EventEmitter.call(this); } 

it 'inherits' from EventEmitter, but what does the call() method actually do?

Answer 1

Basically, Dog is supposedly a constructor with a property name. The EventEmitter.call(this), when executed during Dog instance creation, appends properties declared from the EventEmitter constructor to Dog.

Remember: constructors are still functions, and can still be used as functions.

//An example EventEmitter function EventEmitter(){   //for example, if EventEmitter had these properties   //when EventEmitter.call(this) is executed in the Dog constructor   //it basically passes the new instance of Dog into this function as "this"   //where here, it appends properties to it   this.foo = 'foo';   this.bar = 'bar'; }  //And your constructor Dog function Dog(name) {     this.name = name;     //during instance creation, this line calls the EventEmitter function     //and passes "this" from this scope, which is your new instance of Dog     //as "this" in the EventEmitter constructor     EventEmitter.call(this); }  //create Dog var newDog = new Dog('furball'); //the name, from the Dog constructor newDog.name; //furball //foo and bar, which were appended to the instance by calling EventEmitter.call(this) newDog.foo; //foo newDoc.bar; //bar 

Answer 2

EventEmitter.call(this); 

This line is roughly equivalent to calling super() in languages with classical inheritance.