循环不能正确执行函数操作

Question

我试图让嵌套的循环执行签入/签出模拟。我有我的函数设置和循环在最后，但它总是给我相同的输出。每一位赞助人都有同样数量的书籍和巨额罚款，而不是像checkOut和isOverdue函数那样完全随机化。

如何使循环使用从函数中随机生成的数据，并给每个用户不同数额的罚款和不同的账簿检查？项目说明。

我的代码：

​

    var Book = function(title, Available, publicationDate, checkoutDate, callNumber, Authors) {
        this.title = title;
        this.Available = Available;
        this.publicationDate = publicationDate;
        this.checkoutDate = checkoutDate;
        this.callNumber = callNumber;
        this.Authors = Authors;
    };

    var Author = function(firstName, lastName) {
        this.firstName = firstName;
        this.lastName = lastName;
    };

    var Patron = function(firstName, lastName, libCardNum, booksOut, fine) {
        this.firstName = firstName;
        this.lastName = lastName;
        this.libCardNum = libCardNum;
        this.booksOut = booksOut;
        this.fine = fine;
    };

    function randInRange(start, end) {
        return Math.floor(Math.random() * (end - start + 1)) + start;
    }

    Book.prototype.checkOut = function() {
        this.Available = false;
        var dateChk = new Date();
        var randDay = randInRange(1, 25);
        dateChk.setDate(dateChk.getDate() - randDay);
        this.checkoutDate = dateChk;
    };

    Book.prototype.checkIn = function() {
        this.Available = true;
    };

    Book.prototype.isOverdue = function() {
        var singleDay = 1000 * 60 * 60 * 24;
        var todayDate = new Date().getTime();
        var difference = todayDate - this.checkoutDate.getTime();
        if (Math.round(difference / singleDay) >= 14) {
            return true;
        }
        return false;
    };

    Patron.prototype.read = function(book) {
        this.booksOut.add(book);
    }

    Patron.prototype.return = function(book) {
        this.booksOut.remove(this.booksOut.length);
    }

    var authors = [];
    authors[0] = new Author("Auth", "One");
    authors[1] = new Author("AutL", "Two");

    var catalog = [];
    catalog[0] = new Book('Bk1', true, new Date(2001, 1, 21), new Date(), 123456, authors);
    catalog[1] = new Book('Bk2', true, new Date(2002, 2, 22), new Date(), 987656, authors);
    catalog[2] = new Book('Bk3', true, new Date(2003, 3, 23), new Date(), 092673, authors);
    catalog[3] = new Book('Bk4', true, new Date(2004, 4, 24), new Date(), 658342, authors);
    catalog[4] = new Book('Bk5', true, new Date(2005, 5, 25), new Date(), 345678, authors);

    var patrons = [];
    patrons[0] = new Patron('Pat1', 'Wat', 1, catalog, 0.00);
    patrons[1] = new Patron('Pat2', 'Wot', 1, catalog, 0.00);
    patrons[2] = new Patron('Pat3', 'Wit', 1, catalog, 0.00);
    patrons[3] = new Patron('Pat4', 'Wet', 1, catalog, 0.00);
    patrons[4] = new Patron('Pat5', 'Wut', 1, catalog, 0.00);

    //while loop or for loop for 90 days
      //For loop over catalog
         //forloop over patrons 
             //Check if available , if so check book out
             //If not available check book back in
                 //check checking back in check to see if book is overdue and if so add a fine
    //When down loop over patrons to see their fees

    for (var i = 0; i < 90; i++) {
        for (var j = 0; j < catalog.length; j++) {
            for (var k = 0; k < patrons.length; k++) {
                var fine = patrons[k].fine;
                if (catalog[k].Available) {
                    catalog[k].checkOut;
                } else {
                    catalog[k].checkIn;
                    patrons[k].read;
                }
                if (catalog[k].isOverdue) {
                    fine = fine + 5.00;
                }
                patrons[k].fine = fine;
            }
        }
    }

    for (i = 0; i < patrons.length; i++) {
        console.log(patrons[i].firstName + " has checked out the following books:");
        for (j = 0; j < patrons[i].booksOut.length; j++) {
            console.log(patrons[i].booksOut[j].title);
        }
        console.log(patrons[i].firstName + " has fine amount: $" + patrons[i].fine);
    }

​

Answer 1

我必须对你的例子做一些修改，这样它才能真正发挥作用。

需要知道的一件非常重要的事情是，当调用对象的方法时，必须在调用后面加上括号:不是catalog[j].checkOut，而是catalog[j].checkOut()。

您现在可以检查我的更改以及脚本是如何工作的。有了这个手边，你就可以制定后续问题。

希望这能有所帮助。

​

var Book = function(title, Available, publicationDate, checkoutDate, callNumber, Authors) {
        this.title = title;
        this.Available = Available;
        this.publicationDate = publicationDate;
        this.checkoutDate = checkoutDate;
        this.callNumber = callNumber;
        this.Authors = Authors;
    };

    var Author = function(firstName, lastName) {
        this.firstName = firstName;
        this.lastName = lastName;
    };

    var Patron = function(firstName, lastName, libCardNum, booksOut, fine) {
        this.firstName = firstName;
        this.lastName = lastName;
        this.libCardNum = libCardNum;
        this.booksOut = booksOut;
        this.fine = fine;
    };

    function randInRange(start, end) {
        return Math.floor(Math.random() * (end - start + 1)) + start;
    }

    Book.prototype.checkOut = function() {
        this.Available = false;
        var dateChk = new Date();
        var randDay = randInRange(1, 25);
        dateChk.setDate(dateChk.getDate() - randDay);
        this.checkoutDate = dateChk;
    };

    Book.prototype.checkIn = function() {
        this.Available = true;
    };

    Book.prototype.isOverdue = function() {
        var singleDay = 1000 * 60 * 60 * 24;
        var todayDate = new Date().getTime();
        var difference = todayDate - this.checkoutDate.getTime();
        if (Math.round(difference / singleDay) >= 14) {
            return true;
        }
        return false;
    };
    
    // Changed the read method
    Patron.prototype.read = function(book) {
        this.booksOut[book.callNumber] = book;
    }

    // Changed the return method
    Patron.prototype.return = function(book) {
        delete(this.booksOut[book.callNumber]);
    }

    var authors = [];
    authors[0] = new Author("Auth", "One");
    authors[1] = new Author("AutL", "Two");

    var catalog = [];
    catalog[0] = new Book('Bk1', true, new Date(2001, 1, 21), new Date(), 123456, authors);
    catalog[1] = new Book('Bk2', true, new Date(2002, 2, 22), new Date(), 987656, authors);
    catalog[2] = new Book('Bk3', true, new Date(2003, 3, 23), new Date(), 092673, authors);
    catalog[3] = new Book('Bk4', true, new Date(2004, 4, 24), new Date(), 658342, authors);
    catalog[4] = new Book('Bk5', true, new Date(2005, 5, 25), new Date(), 345678, authors);

    // Changed how Patrons are initialised. Instead of passing the full
    // catalog for booksRead an empty object is passed.
    var patrons = [];
    patrons[0] = new Patron('Pat1', 'Wat', 1, {}, 0.00);
    patrons[1] = new Patron('Pat2', 'Wot', 1, {}, 0.00);
    patrons[2] = new Patron('Pat3', 'Wit', 1, {}, 0.00);
    patrons[3] = new Patron('Pat4', 'Wet', 1, {}, 0.00);
    patrons[4] = new Patron('Pat5', 'Wut', 1, {}, 0.00);

    //while loop or for loop for 90 days
      //For loop over catalog
         //forloop over patrons 
             //Check if available , if so check book out
             //If not available check book back in
                 //check checking back in check to see if book is overdue and if so add a fine
    //When down loop over patrons to see their fees

    for (var i = 0; i < 3; i++) {
        // changed the for loop
        for (var j in catalog) {
            // changed the for loop
            for (var k in patrons) {
                var fine = patrons[k].fine;
                // Changed catalog[k] to catalog[j]
                // moved and changed patrons[k].read() call
                // added the patrons[k].return() call
                if (catalog[j].Available) { 
                    catalog[j].checkOut();
                    patrons[k].read(catalog[j]);
                } else if (patrons[k].booksOut[catalog[j].callNumber]) {
                    catalog[j].checkIn();
                    patrons[k].return(catalog[j]);
                }
                if (catalog[j].isOverdue()) {
                    fine = fine + 5.00;
                }
                patrons[k].fine = fine;
            }
        }
    }

    for (i = 0; i < patrons.length; i++) {
        console.log(patrons[i].firstName + " has checked out the following books:");
        for (j in patrons[i].booksOut) {
            console.log(patrons[i].booksOut[j].title);
        }
        console.log(patrons[i].firstName + " has fine amount: $" + patrons[i].fine);
    }

​

编辑

回答评论。

这是您如何设置for循环的结果。在第一天，所有的书都交给第一位赞助人，第二天，他们去第二次会议等等。

1. 第一天，第一本书，第一本:书是可以买到的，并交给第一赞助人。
2. 第一天，第一本，第二册:没有书。
3. ..。
4. 第一天，第二册，赞助人第一天:书可供使用，并提供给第一赞助人。
5. 第一天，第二册，第二天:没有书。
6. ..。
7. 第二天，第一本书，第一本:没有书，书还了。
8. 第二天，第一册，赞助人第二天:书可以买到，并提供给第二赞助人。
9. 第二天，第一册，赞助人第三天:没有书。
10. ..。
11. 诸若此类

Answer 2

说明没有说要洗牌书籍或赞助人，在模拟期间，这样你的结果就不会像你希望的那样随机。此外，我们还可以使用标准的forEach和普通的for循环来循环书籍和赞助者，从而使代码更容易理解。为了获得更好的结果，我在每个循环中使用_.shuffle随机化书籍和赞助者。我们也可以隐藏精细的逻辑，在我们的赞助人返回原型，最后用一个简单的模拟。

for (var i = 0; i < 90; i++) {
  _.shuffle(books).forEach(function(book) {
    _.shuffle(patrons).forEach(function(patron) {
      if (patron.hasBookCheckedOut(book)) {
        return patron.return(book);
      }

      if (book.available) {
        patron.read(book);
      }     
    });
  });
};

工作实例http://jsbin.com/teyipak/1/edit?js,console