javascript - 循环遍历数组，但即使 “else” 语句为 true 也执行 “if” 语句 (javascript)

Question

在循环中我不确定我是否犯了错误或错误的代码。当我单独运行 if 语句时，它有效。但是当我与“else if”语句一起运行它时。 if 语句失败，else if 语句有效，即使第一个 if 语句为 true。

https://www.freecodecamp.com/challenges/profile-lookup

//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 < contacts.length; i++) {
  if ( contacts[i].firstName === firstName  &&     contacts[i].hasOwnProperty(prop) ) {
    return contacts[i][prop];


}  else if( contacts[i].firstName !== firstName ) {
  return "No such contact";  
    }
  }
// Only change code above this line
}

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

Answer 1

将“没有这样的联系人”回复移到循环之外:

function lookUpProfile(firstName, prop) {
  var match = false;
  for (var i = 0; i < contacts.length; i++) {
    if (contacts[i].firstName === firstName) {
      match = true;
      var valid = contacts[i].hasOwnProperty(prop);
    }
    if (match && valid) {
      return contacts[i][prop];
    }
    if (match && !valid) {
      return "No such property";
    }
  }
  return "No such contact";  
}

假设:每个人存储在一张卡中。

这段代码会迭代所有联系人，当当前联系人符合条件时，会立即返回。当循环结束时，表示没有匹配到的联系人，因此返回相应的回复。

我更喜欢这种没有嵌套 if 的编码方式，但您可以重写内部 for 代码，如下所示:

if (contacts[i].firstName === firstName) {
  if (contacts[i].hasOwnProperty(prop)) {
    return contacts[i][prop];
  } else {
    return "No such property";
  }
}