我正在创建一个包含三个类的数字图书馆:图书馆、书架和书籍。书架上的内容是一系列书籍。书籍有两种方法,enshelf 和 unshelf。当一本书被取消上架时,它应该设置从其所在的书架中删除其自身的实例,然后将其位置属性设置为 null。我怎样才能修改它所在的架子?在构造函数中,如果我更改 this.location,它只会为该属性提供一个新值,而不是修改它指向的变量。我觉得这真的很简单,我忽略了一些非常基本的东西。
var _ = require('lodash');
//books
var oldMan = new Book("Old Man and the Sea", "Ernest Hemingway", 0684801221);
var grapes = new Book("The Grapes of Wrath", "John Steinbeck", 0241952476);
var diamondAge = new Book("The Diamond Age", "Neal Stephenson", 0324249248);
//shelves
var shelf0 = new Shelf(0);
var shelf1 = new Shelf(1);
//libraries
var myLibrary = new Library([shelf0, shelf1], "123 Fake Street");
//these need to accept an unlimited amount of each
function Library(shelves, address) {
this.shelves = shelves; //shelves is an array
this.address = address;
this.getAllBooks = function() {
console.log("Here are all the books in the library: ");
for (var i = 0; i < this.shelves.length; i++) {
console.log("Shelf number " + i + ": ");
for (var j = 0; j < this.shelves[i].contents.length; j++) {
console.log(this.shelves[i].contents[j].name);
}
}
}
}
function Shelf(id) {
this.id = id;
this.contents = [];
}
function Book(name, author, isbn) {
this.name = name;
this.author = author;
this.isbn = isbn;
this.location = null;
this.enshelf = function(newLocation) {
this.location = newLocation;
newLocation.contents.push(this);
}
this.unshelf = function() {
_.without(this.location, this.name); //this doesn't work
this.location = null;
}
}
console.log("Welcome to Digital Library 0.1!");
oldMan.enshelf(shelf1);
myLibrary.getAllBooks();
oldMan.unshelf();
myLibrary.getAllBooks();
最佳答案
您的unshelf
方法存在小问题,很容易修复:
this.unshelf = function() {
this.location.contents =
_.without(this.location.contents, this);
this.location = null;
}
但是请考虑,shelf
和 unshelf
应该是 Shelf
的方法,而不是 Book
的方法。另外,如果您必须使用此方法,请用防护罩包围它,如下所示:
this.unshelf = function() {
if (this.location) {
this.location.contents =
_.without(this.location.contents, this);
this.location = null;
}
}
关于Javascript:从指针修改对象,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/25954108/