Question

我正在执行上面引用的活动，其中程序需要按姓氏搜索条目，找到该条目，然后返回与姓氏匹配的所有条目的名字和姓氏。可以找到活动here。

我的代码在运行后显示正确的消息（Bob Jones），但它附带一条错误消息：＆＃34; TypeError：无法读取属性＆＃39; lastName＆＃39;未定义＆＃34;

我无法弄清楚错误消息的来源，以及如何解决它。欢迎提出任何意见。

我的代码：

var bob = {
    firstName: "Bob",
    lastName: "Jones",
    phoneNumber: "(650) 777-7777",
    email: "bob.jones@example.com"
};

var mary = {
    firstName: "Mary",
    lastName: "Johnson",
    phoneNumber: "(650) 888-8888",
    email: "mary.johnson@example.com"
};

var contacts = [bob, mary];

function printPerson(person) {
    console.log(person.firstName + " " + person.lastName);
}

function list() {
    var contactsLength = contacts.length;
    for (var i = 0; i < contactsLength; i++) {
        printPerson(contacts[i]);
    }
}

/*Create a search function
then call it passing "Jones"*/
function search(lastName) {
    for (var i = 0; i <= contacts.length; i++) {
        if (contacts[i].lastName === lastName) {
            printPerson(contacts[i]);    
        }    
    }    
};
search("Jones");

Answer 1

for中的search()循环循环次数过多。

你在list()中做得对，但在search()中，你犯了一点错误。

你有：

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

应该是：

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

Answer 2

var bob = {
    firstName: "Bob",
    lastName: "Jones",
    phoneNumber: "(650) 777-7777",
    email: "bob.jones@example.com"
};

var mary = {
    firstName: "Mary",
    lastName: "Johnson",
    phoneNumber: "(650) 888-8888",
    email: "mary.johnson@example.com"
};

var contacts = [bob, mary];

// printPerson added here
var printPerson = function(person){

    console.log(contacts[0].firstName + " " + contacts[0].lastName);
    console.log(contacts[1].firstName + " " + contacts[1].lastName);
};

printPerson(contacts[0]);
printPerson(contacts[1]);

Answer 3

var bob = {
    firstName: "Bob",
    lastName: "Jones",
    phoneNumber: "(650) 777-7777 FREE",
    email: "bob.jones@example.com"
};

var mary = {
    firstName: "Mary",
    lastName: "Johnson",
    phoneNumber: "(650) 888-8888 FREE",
    email: "mary.johnson@example.com"
};

var contacts = [bob, mary];

function printPerson(person) {
    console.log(person.firstName + " " + person.lastName);
}

function list() {
    var contactsLength = contacts.length;
    for (var i = 0; i < contactsLength; i++) {
        printPerson(contacts[i]);
    }
}

function search(lastName) {
    var contactsLength = contacts.length;
    for (var i = 0; i < contactsLength; i++) {
        if (lastName === contacts[i].lastName) {
            printPerson(contacts[i]);
        };
    };
};
search("Jones");

function add(firstName, lastName, email, phoneNumber){
    object = {
        firstName: firstName,
        lastName: lastName, 
        email: email, 
        phoneNumber: phoneNumber
    };
    contacts[contacts.length] = object;
};

add("firstName", "lastName", "name@example.com", "32874683275");
list();

Codecademy构建地址簿5/6

3 个答案: