4.03 - the extend function.js

JS设计模式源代码

/* Extend function. */

function extend(subClass, superClass) {
  var F = function() {};
  F.prototype = superClass.prototype;
  subClass.prototype = new F();
  subClass.prototype.constructor = subClass;
}


/* Class Person. */

function Person(name) {
  this.name = name;
}

Person.prototype.getName = function() {
  return this.name;
}

/* Class Author. */

function Author(name, books) {
  Person.call(this, name);
  this.books = books;
}
extend(Author, Person);

Author.prototype.getBooks = function() {
  return this.books;
};



/* Extend function, improved. */

function extend(subClass, superClass) {
  var F = function() {};
  F.prototype = superClass.prototype;
  subClass.prototype = new F();
  subClass.prototype.constructor = subClass;

  subClass.superclass = superClass.prototype;
  if(superClass.prototype.constructor == Object.prototype.constructor) {
    superClass.prototype.constructor = superClass;
  }
}


/* Class Author. */

function Author(name, books) {
  Author.superclass.constructor.call(this, name);
  this.books = books;
}
extend(Author, Person);

Author.prototype.getBooks = function() {
  return this.books;
};

Author.prototype.getName = function() {
  var name = Author.superclass.getName.call(this);
  return name + ', Author of ' + this.getBooks().join(', ');
};