Question

我的代码似乎返回未在对象中明确声明的空值。

我要编写的代码是将遍历对象数组的代码，找到哪个值为null，然后添加一个等于“嗨”的“ question”（问题）键，请问您能否提供“ key”。 “最后，我想用问号返回对象数组。

请参见下面的代码：

var list1 = [
  { firstName: null, lastName: 'I.', country: 'Argentina', continent: 'Americas', age: 35, language: 'Java' },
  { firstName: 'Lukas', lastName: 'X.', country: 'Croatia', continent: 'Europe', age: 35, language: null },
  { firstName: 'Madison', lastName: 'U.', country: 'United States', continent: 'Americas', age: 32, language: 'Ruby' } 
];

function askForMissingDetails(list) {
    for (let i = 0; i < list.length; i++) {
      for (var prop in list[i]) {
        if ( list[i].prop == null) 
          list[i]['question'] = `Hi, could you please provide your ${prop}.`;
        else 
          list.splice(i,1);
      }
    }
  return list;
}

console.log(askForMissingDetails(list1))

我得到的输出是：

[
0:  {
firstName:  null
lastName:   "I."
country:    "Argentina"
continent:  "Americas"
age:    35
language:   "Java"
question:   "Hi, could you please provide your question."
}
1:  {
firstName:  "Lukas"
lastName:   "X."
country:    "Croatia"
continent:  "Europe"
age:    35
language:   null
question:   "Hi, could you please provide your question."
}
2:  {
firstName:  "Madison"
lastName:   "U."
country:    "United States"
continent:  "Americas"
age:    32
language:   "Ruby"
question:   "Hi, could you please provide your language."
}]

Answer 1

似乎您在混淆访问对象的方式。首先，您正在阅读list[i].prop。这将寻找一个实际上叫做prop的属性。要解决此问题，请将其更改为list[i][prop]。在这种情况下，方括号表示动态查找。您不是在寻找prop键，而是在寻找prop 的值的键。

Answer 2

如果您的对象中有多个null值，我会使用reduce来创建一个新的列表，并带有属性问题以保留在数组中：

var list1 = [
  {
    firstName: null,
    lastName: "I.",
    country: "Argentina",
    continent: "Americas",
    age: 35,
    language: "Java"
  },
  {
    firstName: "Lukas",
    lastName: "X.",
    country: "Croatia",
    continent: "Europe",
    age: 35,
    language: null
  },
  {
    firstName: "Madison",
    lastName: "U.",
    country: "United States",
    continent: "Americas",
    age: 32,
    language: "Ruby"
  },
  {
    firstName: "Christian",
    lastName: null,
    country: "Perú",
    continent: null,
    age: 32,
    language: null
  }
];

// using list1 as context to apply reduce to be saved on myNewList
const myNewList = list1.reduce((acc, item) => {
  // itering keys names of the current object
  Object.keys(item).forEach(key => {
    // if the current key name his value is null
    if (!item[key]) {
      // if haven't a key name called question, i create it as a new empty array
      if (!item.question) item.question = [];
      // pushing into the array the message with the current key name(because is null) 
      item.question.push(`Hi, could you please provide your ${key}.`);
    }
  });
  // pushing into the accumulator the current object
  if (item.question) acc.push(item);
  return acc;
}, []);

console.log(myNewList);

Answer 3

let result = list1.reduce((acc, list) => {
    let missedKey = "";
    for(let key in list){
        if(!list[key]) missedKey = key
    }
    if(missedKey) { 
        list.question = `Hi, could you please provide your ${missedKey}.` 
        acc.push(list)
    };
    return acc;
}, []);

Answer 4

我相信您要执行的是 map / reduce 操作。

您想更改原始数组，以包含存在getCutPlanes值（“映射” ）的问题，并过滤出完整的条目（“ reduce” < / em>）。

这一切都可以使用Array.prototype.reduce()
完成

viewer.getCutPlanes() //[n.Vector4]0: n.Vector4 {x: 0.5455882464475988, y: 0, z: 0.8380533785733665, w: 2.9219428579920317}length: 1__proto__: Array(0)

我的对象是否返回隐藏的“空”值？

4 个答案: