Question

所以我通过freecodecamp解决了那里的问题，与编程保持一致，我偶然发现了一个障碍，我并不完全确定有什么不对。

所以我有一个名为contacts的对象数组，我需要创建一个名为lookUp(firstName, prop)的函数。作业的文本是这样的：

该函数应检查firstName是否为实际联系人firstName，并且给定属性（prop）是该联系人的属性。

如果两者都为真，则返回＆＃34;值＆＃34;该财产。

如果firstName与任何联系人不对应，则返回＆＃34;没有此类联系人＆＃34;

如果prop与任何有效的属性不对应，则返回＆＃34;没有此类属性＆＃34;

代码：

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": ["Intruiging Cases", "Violin"]
    },
    {
        "firstName": "Kristian",
        "lastName": "Vos",
        "number": "unknown",
        "likes": ["Javascript", "Gaming", "Foxes"]
    },
];


function lookUp( firstName, prop ){
  for( var i = 0; i < contacts.length; i++ ){
    if( contacts[i].firstName == firstName ) {
      if( contacts[i].hasOwnProperty( prop ) ) {
        return contacts[i].prop;
      } else {
        return "No such property";
      }
    } else {
      return "No such contact";
    } 
  }
}

// Change these values to test your function
lookUp("Kristian", "lastName");

所以我循环遍历数组，for循环检查每个对象。在第一个if中，我检查该对象的firstName属性是否等于函数参数firstName，如果它是真的，我检查该对象是否具有属性prop，我应该能够归还它。但似乎

return contacts[i].prop;

不起作用，我有点迷失为什么。我确定它是微不足道的，但我不明白为什么。当我去控制台，并测试

contacts[0].likes

我离开了数组["Pizza", "Coding", "Brownie Points"]，但是如果我不能正常工作的话。我在这里做错了什么？

修改

好的，我试过

function lookUp( firstName, prop ){
  for( var i = 0; i < contacts.length; i++ ){
    if( contacts[i].firstName == firstName ) {
      if( contacts[i].hasOwnProperty( prop ) ) {
        return contacts[i][prop];
      } else {
        return "No such property";
      }
    } else {
      return "No such contact";
    } 
  }
}

但我仍然得到同样的错误：\

Answer 1

好的我傻了，我太早退出了我的循环：

function lookUp( firstName, prop ){
  for( var i = 0; i < contacts.length; i++ ){
    if( firstName == contacts[i].firstName ) {
      if( contacts[i].hasOwnProperty( prop ) ) {
        return contacts[i][prop];
      } else {
        return "No such property";
      }
    }
  }
  return "No such contact";
}

这很有效。

Answer 2

我认为你对返回的做法感到困惑。您的代码只会执行一次迭代return "No such contact"。返回立即停止执行的功能。这是我用console.log https://jsfiddle.net/oegw3a4y/

表达的意思的小提琴

在您的情况下，第一次迭代在第一个if语句中的计算结果为false，并立即转到else。

Answer 3

function lookUp(firstName, prop){
  var ans="";
  for(var i=0;i<contacts.length;i++){

//if firstname matches,fetch the property
if(contacts[i].firstName==firstName)
  {
    //in the item matched with first name check if the property is there or not.
    if(contacts[i].hasOwnProperty(prop))
    {
       ans=contacts[i][prop];
    }
    else{
      ans="No such property";
    }

  }
  }

  // if no contact found after searching entire collection.then ans will be empty
  if(ans==="") ans="No such contact";  
  return ans;
}

Answer 4

返回调用需要是堆栈中的最后一件事。上面的代码不起作用，因为在循环迭代到下一个增量之前函数返回“No such contact”！以下作品：

//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(firstName, prop){
// Only change code below this line
  for ( var i = 0; i <= 3; i++ ) {
    if (contacts[i].firstName == firstName) {
      if ( contacts[i].hasOwnProperty(prop) === true) {
        return contacts[i][prop];
        } 
        return "No such property";

    }    
  }
  return "No such contact";
// Only change code above this line
}

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

Answer 5

＆＃13;

# make gensim dictionary and corpus
dictionary = gensim.corpora.Dictionary(boc_texts)
corpus = [dictionary.doc2bow(boc_text) for boc_text in boc_texts]
tfidf = gensim.models.TfidfModel(corpus)
corpus_tfidf = tfidf[corpus]

＆＃13;

Answer 6

function lookUpProfile(firstName, prop){
// Only change code below this line
for (var i = 0; i < contacts.length; i++) {
  if (firstName === contacts[i].firstName && contacts[i].hasOwnProperty(prop)) {
    return contacts[i][prop];
  }
}

for (var j = 0; j < contacts.length; j++) {
  if (firstName === contacts[j].firstName && contacts[j].hasOwnProperty(prop) === false) {
    return 'No such property';
  }
}
    return 'No such contact';
// Only change code above this line
}

Answer 7

以下是我使用迄今为止在FCC中提供的工具所做的工作。

var o = "";

function lookUp(firstName, prop) {
for (i = 0; i <= contacts.length - 1; i++) {
       if (firstName === contacts[i].firstName && (contacts[i][prop])) {
           return (contacts[i][prop]);
   }
   }
// if property look up returns undefined type then there is no such property
        if ((contacts[0][prop]) === undefined) {
         o = "No such property";
     } else {
         o = "No such contact";
     }   
    return o;   
}

在freecode阵营检查站上查找配置文件

7 个答案: