javascript - 尝试访问数组: family[i] is undefined

Question

我试图按顺序打印每个人的姓名，但我不断收到此错误family[i] is undefined。

function Person (name, age) {
    this.name = name;
    this.age = age;
}

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);

for(var i = 0; i <= family.length; i++) {
    console.log(family[i].name);
}

Answer 1

您的for循环超出了数组的范围。尝试:

for( var i = 0; i < family.length; i++ )

请记住 array.length将始终高于最大数组索引，因为索引从 0 开始，而长度从 1 开始。