Use Object.create() to create Object - Node.js Object

Node.js examples for Object:Object Operation

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Description

Use Object.create() to create Object

Demo Code


function Person(firstName, lastName) {
  this.firstName = firstName;/*w  w w.jav a 2 s  . c  o m*/
  this.lastName = lastName;
//  this.kind = "Person";
//  this.name = function() { return this.firstName + " " + this.lastName; };
}

// New: Moved down from Constructor Function for better code reuse by adding properties to prototype object
// Note: prototype only applies with new keyword
Person.prototype.kind = "Person"; 

// Note: Function properties behave like static members                                                    
Person.kindStatic = "Person Static";                                                    
Person.prototype.name = function() { return this.firstName + " " + this.lastName; };

// New: Or shortcut
Person.prototype = {
  kind: "Person",
  name: function() { return this.firstName + " " + this.lastName; }
}

var fred1 = { firstName: "Fred", lastName: "Flintstone", kind: "Person", name: function() { return this.firstName + " " + this.lastName; } };
var barney1 = { firstName: "Barney", lastName: "Rubble", kind: "Person", name() { return this.firstName + " " + this.lastName; } };

// Create objects using Constructor function
var fred2 = new Person("Fred", "Flintstone");
var barney2 = new Person("Barney", "Rubble");


var fred3 = Object.create(fred1);
var barney3 = Object.create(barney2);
var PersonCopy = Object.create(Person);                     

console.log(fred3);
console.log(fred3.name());
console.log(barney3);
console.log(barney3.name());
console.log(PersonCopy);


// New: prototype with Object.create()                            
console.log("");
console.log("*** prototype with Object.create() ***");

var person = {
  kind: "Person",
  name: function() { return this.firstName + " " + this.lastName; }
};

var fred4 = Object.create(person);
fred4.firstName = "Fred";
fred4.lastName = "Flintstone";

// or pass object literal to Object.create()
fred4 = Object.create(person, {
    firstName: { value: "Fred" },
    lastName: { value: "Flintstone" }
});

console.log(fred4);                                                     // Object {firstName: "Fred", lastName: "Flintstone"}
console.log(fred4.name());                                              // Fred Flintstone

console.log(Object.getPrototypeOf(person));                             // Object {...}                 
console.log(person.__proto__);                                          // Object {...} 
console.log(Object.getPrototypeOf(fred4));                              // Object {kind: "Person", name: function}
console.log(fred4.__proto__);                                           // Object {kind: "Person", name: function}


// Deep Dive
console.log("");
console.log("*** Deep Dive ***");

console.log(Person.prototype.prototype);                                // undefined (because prototype is a function property only)
console.log(Person.prototype.__proto__);                                // Object { ... }
console.log(Object.getPrototypeOf(Object.getPrototypeOf(fred2)));       // Object { ... }
console.log(Person.constructor);                                        // function Function() { [native code] }
console.log(fred2.constructor);                                         // function Person(firstName, lastName) { ... }
console.log(fred2 instanceof Person);                                   // true
console.log(Person.prototype === fred2.__proto__);                      // true

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