JavaScript Objects

constructors_can_take_params.js

function Human(name, age) {
  this.name = name;
  this.age = age;
}

bob = new Human("bob", 30);

bob.name;     // "bob"
bob.age;      // 30

constructors_have_a_prototype.js

function Human(name, age) {
  this.name = name;
  this.age = age;
}

Human.prototype;      // {}

Human.prototype.sayHello = function() {
  return "Hi, I'm " + this.name + "!";
};

Human.sayHello;       // undefined

functions_are_objects.js

function foo(a, b) {
  return a * b;
}

foo(3, 4);               // 12

foo.a = "abc";
foo.a;                   // "abc"

foo.bar = function() {
  "baz"
};
foo.bar();               // "baz"

making_objects.js

{} == new Object();

object_properties.js

b = {
  "name":"Bob",
  age: 30
};

b.name;               // "Bob"
b["age"];             // 30

b.breathes = "air";
b.breathes;           // "air"

objects_contain_objects.js

b = {
  "name":"Bob",
  age: 30
};

b.child = {
  age: 5
}
b.child.age;          // "age"

objects_have_constructors.js

a = {};
a.constructor; // function Object() { ... }

b = new Object();
b.constructor; // function Object() { ... }

our_own_functions_can_be_constructors.js

function Human() {
  this.breathes = "air";
}

bob = new Human();
bob.breathes;             // "air"
bob.constructor; // function Human() { ... }

prototypes_add_to_constructed_objects.js

bob = new Human("bob", 30);

bob.constructor;           // function Human() { ... }

bob.constructor.prototype; // { sayHello: ... }

bob.sayHello();            // "Hi, I'm Bob!"

replacing_a_functions_constructor.js

function Animal() {
  this.breathes = "air";
}

function Human(name, age) {
  this.name = name;
  this.age = age;
}

Human.prototype = new Animal();

bob = new Human("bob", 30);
bob.breathes;        // "air"

bob.constructor;     // function Animal() { ... }

Human.prototype.constructor = Human;

bob.constructor;     // function Human() { ... }