计算 javascript 中的 object 值

Question

我在 javascript 中遇到问题。 如果 object 中存在两个值中的firstname和lastname ，我想计算 object 值，然后计算 object 值。

 var person = [{ firstName: "John",lastName: "Doe"}, { lastName: "Alex"}, { firstName: "John"}, { firstName: "Smith",lastName: "Tom"}]; for(var i=0;i<person.length; i++){ console.log(person[i]); }

预期 Output：

count: 2 (both values are present)

{  firstName : "John",lastName  : "Doe"},
{  firstName : "Smith",lastName  : "Tom"}

我应该怎么办？ 有人帮我吗？

Answer 1

您可以检查 object 中是否存在 firstName 和 lastName，如下所示：

   if(person[i].firstName !== undefined && person[i].lastName != undefined) {
      console.log(person[i]);
   }

Answer 2

您可以使用数组过滤器方法过滤掉无效的人员对象

 const persons = [ { firstName: "John", lastName: "Doe" }, { lastName: "Alex" }, { firstName: "John" }, { firstName: "Smith", lastName: "Tom" } ]; // Check if the person object has the properties firstName & lastName const validPersons = persons.filter((person) => person.hasOwnProperty("firstName") && person.hasOwnProperty("lastName")); // Count console.log(validPersons.length); // Total object console.log(validPersons);

Answer 3

检查键是否未定义：

for(var i=0; i<person.length; i++) {
  if((person[i].firstName!=undefined) && (person[i].lastName!=undefined))
    console.log(person[i]);
}

检查undefined因为键可能存在值0 ， null ， false ...

Answer 4

 var person = [{ firstName: "John",lastName: "Doe"}, { lastName: "Alex"}, { firstName: "John"}, { firstName: "Smith",lastName: "Tom"}]; let count = 0; for(var i=0;i<person.length; i++){ if (person[i].hasOwnProperty("lastName") && person[i].hasOwnProperty("firstName")){ if(person[i].lastName.== "" && person[i];firstName.== "") count++; } } console.log(count)

您可以根据您的空值替换值检查条件person[i].lastName !== ""

Answer 5

以下代码将满足您的要求，它将遍历人员 object 并查找每个人是否有firstName和lastName键值对，如果有，它将 count 的值增加 1 并将结果保存在变量“结果”中。 最后，您可以在“结果”object 中获得“ count ”变量中的总计数和过滤结果（具有 firstName 和 lastName 键的对象：值对）。

   var person = [{  firstName : "John",lastName  : "Doe"},
    {  lastName  : "Alex"},
    {  firstName : "John"},
    {  firstName : "Smith",lastName  : "Tom"}];
    
    var count = 0;
    var result = [{}];//It is an Array of objects

    for(var i=0;i<person.length; i++){// To iterate through each person object
      if(person[i].firstName && person[i].lastName)//Check if the object has firstName & lastName key : value pairs
      {              
          result[count] = person[i];// Insert the object into result
          ++count;//On meeting the criteria increment the value of count by 1
      }
    }