eloquentJavascript.md

ELOQUENT JS -- CONTENTS

new

Just like the notation with braces and colons we have already seen, new is a way to create object values. Instead of specifying all the property names and values, a function is used to build up the object. This makes it possible to define a kind of standard procedure for creating objects. Functions like this are called constructors, and in chapter 8 we will see how to write them.

new

The new keyword provides a convenient way of creating new objects. When a function is called with the word new in front of it, its this variable will point at a new object, which it will automatically return (unless it explicitly returns something else). Functions used to create new objects like this are called constructors. Here is a constructor for rabbits:

function Rabbit(adjective) {
  this.adjective = adjective;
  this.speak = function(line) {
    print("The ", this.adjective, " rabbit says '", line, "'");
  };
}

var killerRabbit = new Rabbit("killer");
killerRabbit.speak("GRAAAAAAAAAH!");

It is convention to start the names of constructors with a capital letter. This makes it easy to distinguish them from other functions.

Why is the new keyword even necessary?

Prototype and Constructor properties