麻煩整合嵌套的和如果循環在Javascript中

Question

我試圖運行庫檢查/結帳系統的模擬。我製作了所有的對象，但在執行模擬本身的循環中遇到了麻煩。我的代碼：

的僞代碼：

//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 

我在這個循環

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

所有代碼

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; 
}; 

Book.prototype.checkOut = function() { 
    this.Available = false; 
    var temp = new Date(1000000000); 
    var date = new Date() - temp; 
    var res = new Date(date); 
    this.checkoutDate = res; 
}; 

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.read = 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); 

var j = 0; 

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

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

你第二次和第三次循環使用相同的迭代變量的嘗試（i）

也許使用不同的名稱

Answer 2

在您的代碼更改重複的變量名i，不要忘記添加var不使它們成爲全球：

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

for (var i = 0; i < patrons.length; i++) { 
    console.log(patrons[i].firstName + " has checked out the following books:"); 
    for (var 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); 
}