構造器與陣列和用於循環顯示錯誤

Question

我的代碼如下

// Our Person constructor 
function Person (name, age) { 
this.name = name; 
this.age = age; 
} 
// Now we can make an array of people 
var family= new Array(); 
family[0]= new Person("alice", 40); 
family[1]= new Person("bob", 42); 
family[2]= new Person("michelle", 8); 
family[3]= new Person("timmy", 6); 

// loop through our new array 
for(var i = 0; i <= family.length; i++) { 
console.log("My name is " + family[i].name); 
} 

唐，t無爲什麼，但它示出了下面

My name is alice 
My name is bob 
My name is michelle 
My name is timmy 

--- 
We're running a test below to make sure your code works. 
My name is aliceMy name is bobMy name is michelleMy name is timmy 
TypeError: family[i] is undefined 

顯示錯誤我不能夠糾正這個。爲我解決它。

Answer 1

i <= family.length 

應該是

i < family.length 

因爲，陣列的indeces從零開始。因此，當您達到i的最大值時，陣列中不存在元素，因此undefined