javascript - freecodecamp 不接受 JS 代码

Question

我正在使用 freecodecamp 并进行以下练习:

https://learn.freecodecamp.org/javascript-algorithms-and-data-structures/basic-javascript/profile-lookup

现在我的代码如下:

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(name, prop) {
  // Only change code below this line
  // Only change code below this line

  for (var i = 0; i < contacts.length; i++) {
    if (contacts[i].firstName == name) {
      foundName += 1;
    }
    if (contacts[i].firstName == name && contacts[i].hasOwnProperty(prop)) {
      return contacts[i][prop];
    } else if (contacts[i].firstName == name && contacts[i].hasOwnProperty(prop) == false) {
      return "No such property";
    }
  }
  if (foundName < 1) {
    return "No such contact"
  };
}

var foundName = 0;

// Only change code above this line


// Change these values to test your function
var ans = lookUpProfile("Bob", "number");
console.log(ans);

因此，我使用 for 循环遍历预定义的数组，并检查 name == firstName 以及对象具有 prop 属性的实例。在这些情况下，我将归还属性(property)。否则，我返回“No such Property”。我还更改了变量foundName，以便当firstName 与循环中的名称匹配时，foundName 获得正值。如果foundName小于1(即没有找到匹配的名字)，那么我返回“没有这样的联系人”。

现在，当我在浏览器中运行它并查看控制台时，它似乎工作得很好。然而，当我在 freecodecamp 中输入这个答案时，我得到:

“Bob”，“number”应返回“No such contact” “Bob”、“potato”应该返回“No such contact”

但是，例如，如果我将“Bob”和“number”放入函数中，我确实会得到“没有这样的联系”...我一定在这里遗漏了一些明显的东西，但我对此感到非常困惑!

Answer 1

问题出在变量foundName中，每次调用函数lookUpProfile时，都会更改全局变量foundName，因此当您调用该函数时** LookUpProfile** 以 'bob' 作为参数，它将返回 undefined 因为 foundName 的值大于 1 ，因此您需要将变量的范围限定为功能 block 作用域，您应该在函数内部而不是外部定义变量 foundName ，也停止使用关键字 var ，而是使用 let

看下面的解决方案

//Setup
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(name, prop) {
  // Only change code below this line
  // Only change code below this line
   let foundName = 0;
  for (var i = 0; i < contacts.length; i++) {
    if (contacts[i].firstName == name) {
      foundName += 1;
    }
    if (contacts[i].firstName == name && contacts[i].hasOwnProperty(prop)) {
      return contacts[i][prop];
    } else if (contacts[i].firstName == name && contacts[i].hasOwnProperty(prop) == false) {
      return "No such property";
    }
  }
  if (foundName < 1) {
    return "No such contact"
  };
}




// Only change code above this line


// Change these values to test your function
// Change these values to test your function
lookUpProfile("Akira", "likes");