//初始化变量
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 lookUp(firstName, prop){
// 请把你的代码写在这条注释以下
    for(var i=0;i<contacts.length;i++){
        if(contacts[i].firstName=== firstName){
            if(contacts[i][prop]){
              return contacts[i][prop];
            }
            return "No such property";
        }
    }
    return "No such contact";
     
// 请把你的代码写在这条注释以上
}
// 你可以修改这一行来测试你的代码
lookUp("Akira", "likes");
原文:http://www.cnblogs.com/qingcui277/p/7573046.html