javascript - 使用 for 循环 JS 遍历数组

Question

我有一个对象数组(联系人)，我需要编写一个函数来检查 firstName (函数的第一个参数) 是否是实际联系人的名字并且给定的属性 (prop 是函数的第二个参数) 是该联系人的属性。如果两者都为真，则返回该属性的“值”。

如果 firstName 不对应于任何联系人，则返回 “No such contact”

如果prop 不对应于任何有效的属性，则返回“没有这样的属性”

我知道我需要做什么，我写的 sudo 但是用实际的 JavaScript 写它我遇到了障碍。

下面是我目前写的:

var contacts = [
    {
        "firstName": "Akira",
        "lastName": "Laine",
        "number": "0543236543",
        "likes": ["Pizza", "Coding", "Brownie Points"]
    },
    {
        "firstName": "Harry",
        "lastName": "Potter",
        "number": "0994372684",
        "likes": ["Hogwarts", "Magic", "Hagrid"]
    },
    {
        "firstName": "Sherlock",
        "lastName": "Holmes",
        "number": "0487345643",
        "likes": ["Intriguing Cases", "Violin"]
    },
    {
        "firstName": "Kristian",
        "lastName": "Vos",
        "number": "unknown",
        "likes": ["Javascript", "Gaming", "Foxes"]
    }
];


function lookUpProfile(firstName, prop) {
    var value;
    for (i = 0; i < 2; i++) {
        if (contacts[i].firstName === true && contacts[i].prop === true) {
            value = contacts[i].prop;
            return value;
        }
    }
}

Answer 1

一旦找到具有给定 firstName 的联系人，您就可以使用跳出循环，然后检查传递的 prop 值并相应地返回消息。

var contacts = [
    {
        "firstName": "Akira",
        "lastName": "Laine",
        "number": "0543236543",
        "likes": ["Pizza", "Coding", "Brownie Points"]
    },
    {
        "firstName": "Harry",
        "lastName": "Potter",
        "number": "0994372684",
        "likes": ["Hogwarts", "Magic", "Hagrid"]
    },
    {
        "firstName": "Sherlock",
        "lastName": "Holmes",
        "number": "0487345643",
        "likes": ["Intriguing Cases", "Violin"]
    },
    {
        "firstName": "Kristian",
        "lastName": "Vos",
        "number": "unknown",
        "likes": ["Javascript", "Gaming", "Foxes"]
    }
];


function lookUpProfile(firstName, prop) {
    var value = undefined;
    for (i = 0; i < contacts.length; i++) {
        if (contacts[i].firstName === firstName) {
            value = contacts[i];
            break;
        }
    }
    
    if(!value) {
        return 'No such contact';
    }
    
    if(!(prop in value)) {
        return 'No such property';
    }

    return value[prop];
}
console.log(lookUpProfile('Sherlock', 'likes'));
console.log(lookUpProfile('Harry', 'friends'));
console.log(lookUpProfile('John', 'likes'));