Question

How do

• prototypes
• objects
• constructors
• “this”
• functions

work in JS in relation to each other (and what exactly are they; is a constructor a function, object, prototype, “this”)?

Can someone please clarify this? I have an idea of what each of them are and how they work, but not a clear one.

I think it would be easier to understand questions that arise, like, for example: “Is a.constructor the same as a.prototype.constructor“, if one knows what these things are.

Answer 1

Object – A collection of name-value pairs, for example:

var someObject = {
    aName: "aValue",
    name2: "value2"
}

Constructor – a function that ‘creates’ an object, for example:

function someObject(someParam) {
    this.someParam = someParam;
    this.getSomeParam = function() {
         return this.someParam;
    }
}

Prototype – a special type of object, from which other objects inherit properties. Every object has a prototype. You can use them to add a method to all instances of an object, for example:

String.prototype.doSomething = function() {
    //Do something with a String
}

Now that you have defined a doSomething method on the String prototype, all String objects can use it:

var myString = "Hello";
myString.doSomething();

For more information about the JavaScript language and how it works, I suggest you take a look at the ECMAScript spec, or for something a bit lighter, read this.