對象VS對象

Question

function Person(idn, dep, nam, age, gen, aut) { 
 
    this.idn = idn; //IDNumber 
 
    this.dep = dep; //Department 
 
    this.nam = nam; //Name 
 
    this.age = age; //Age 
 
    this.gen = gen; //Gender 
 
    this.aut = aut; 
 
    } //Auto 
 

 
function Car(make, modl, year, lice, colo, mile, ownr) { 
 
    this.make = make; //MakeOfTheCar 
 
    this.modl = modl; //ModelOfTheCar 
 
    this.year = year; //Year 
 
    this.lice = lice; //Licence 
 
    this.colo = colo; //ColorOfTheCar 
 
    this.mile = mile; //Mileage 
 
    this.ownr = ownr; 
 
    } //Owner 
 

 
var p01 = new Person(3475, 1, 'Rand,McKinnon', 33, 'M', c01); 
 
var p02 = new Person(7608, 2, 'Ken,Jones', 39, 'M', c02); 
 
var p03 = new Person(1957, 3, 'Vladi,Orlov', 58, 'M', c03); 
 

 
var c01 = new Car('Eagle', 'Talon,TSi', 1993, 'BP456H46', 'red', 201, p01); 
 
var c02 = new Car('Nissan', '300,ZX', 'J001', 1992, 'blue', 244, p02); 
 
var c03 = new Car('Toyota', 'Avalon,XLS', '6HPR64W', 2000, 'black', 118, p03); 
 

 
document.write('Car:c03.make=', c03.make, '|', c03.colo, '|', c03.ownr.nam, '<br>'); 
 
document.write('Person:p03.idn=', p03.idn, '|', p03.nam, '|', p03.gen, '|', p03.aut, '<br>');

末參數（p03.aut）：未定義

需要你的幫助來弄清楚如何使它發揮作用。

Answer 1

當時你執行這行代碼：

var p03 = new Person(1957, 3, 'Vladi,Orlov', 58, 'M', c03); 

c03還沒有價值。因此，您在那裏傳遞undefined值，這就是存儲在p03.aut中的值。當您稍後檢索該值時，它將檢索您先前放在那裏的undefined值。

既然你有一個雞和雞蛋的問題（兩個對象不能同時引用它們的構造函數，因爲它們之一必須先被創建），你將在對象之後設置其中一個參數兩者都已被構建（例如不在構造函數中）。

例如，你可以這樣做：

var p01 = new Person(3475, 1, 'Rand,McKinnon', 33, 'M'); 
var p02 = new Person(7608, 2, 'Ken,Jones', 39, 'M'); 
var p03 = new Person(1957, 3, 'Vladi,Orlov', 58, 'M'); 

var c01 = new Car('Eagle', 'Talon,TSi', 1993, 'BP456H46', 'red', 201, p01); 
var c02 = new Car('Nissan', '300,ZX', 'J001', 1992, 'blue', 244, p02); 
var c03 = new Car('Toyota', 'Avalon,XLS', '6HPR64W', 2000, 'black', 118, p03); 

p01.aut = c01; 
p02.aut = c02; 
p03.aut = c03; 

document.write('Car:c03.make=', c03.make, '|', c03.colo, '|', c03.ownr.nam, '<br>'); 
document.write('Person:p03.idn=', p03.idn, '|', p03.nam, '|', p03.gen, '|', p03.aut, '<br>');