3.02 - fully exposed object.js

JS设计模式源代码

var Book = function(isbn, title, author) {
  if(isbn == undefined) throw new Error('Book constructor requires an isbn.');
  this.isbn = isbn;
  this.title = title || 'No title specified';
  this.author = author || 'No author specified';
}

Book.prototype.display = function() {
        ...
};


/* With ISBN check. */

var Book = function(isbn, title, author) {
  if(!this.checkIsbn(isbn)) throw new Error('Book: Invalid ISBN.');
  this.isbn = isbn;
  this.title = title || 'No title specified';
  this.author = author || 'No author specified';
}

Book.prototype = {
  checkIsbn: function(isbn) {
    if(isbn == undefined || typeof isbn != 'string') {
      return false;
    }

    isbn = isbn.replace(/-/. ''); // Remove dashes.
    if(isbn.length != 10 && isbn.length != 13) {
      return false;
    }

    var sum = 0;
    if(isbn.length === 10) { // 10 digit ISBN.
      If(!isbn.match(\^\d{9}\)) { // Ensure characters 1 through 9 are digits.
        return false;
      }

      for(var i = 0; i < 9; i++) {
        sum += isbn.charAt(i) * (10 - i);
      }
      var checksum = sum % 11;
      if(checksum === 10) checksum = 'X';
      if(isbn.charAt(9) != checksum) {
        return false;
      }
    }
    else { // 13 digit ISBN.
      if(!isbn.match(\^\d{12}\)) { // Ensure characters 1 through 12 are digits.
        return false;
      }

      for(var i = 0; i < 12; i++) {
        sum += isbn.charAt(i) * ((i % 2 === 0) ? 1 : 3);
      }
      var checksum = sum % 10;
      if(isbn.charAt(12) != checksum) {
        return false;
      }
    }

    return true; // All tests passed.
  },

  display: function() {
    ...
  }
};


/* Publication interface. */

var Publication = new Interface('Publication', ['getIsbn', 'setIsbn', 'getTitle',
  'setTitle', 'getAuthor', 'setAuthor', 'display']);


/* With mutators and accessors. */

var Book = function(isbn, title, author) { // implements Publication
  this.setIsbn(isbn);
  this.setTitle(title);
  this.setAuthor(author);
}

Book.prototype = {
  checkIsbn: function(isbn) {
    ...
  },
  getIsbn: function() {
    return this.isbn;
  },
  setIsbn: function(isbn) {
    if(!this.checkIsbn(isbn)) throw new Error('Book: Invalid ISBN.');
    this.isbn = isbn;
  },

  getTitle: function() {
    return this.title;
  },
  setTitle: function(title) {
    this.title = title || 'No title specified';
  },

  getAuthor: function() {
    return this.author;
  },
  setAuthor: function(author) {
    this.author = author || 'No author specified';
  },

  display: function() {
    ...
  }
};