Question

我正在尝试在一系列对象中找到最年长的人。在下面的示例中，我的最终答案应为“ Carly”，因为她已经存活了最长的时间。

我的代码返回了Ray，因为它无法识别Carly仍然活着。

我尝试将代码嵌套在if / else语句中，该语句检查是否存在yearOfDeath值，但显然有问题，因为它仍在返回Ray对象。

let findTheOldest = function(arr) {
    var oldest = 0;
    var oldestPerson = {};
    var today = new Date();
    var yyyy = today.getFullYear();


    arr.reduce((total, person) => {

      if (person.yearOfDeath){
         if ((person.yearOfDeath - person.yearOfBirth) > oldest){
            oldest = person.yearOfDeath - person.yearOfBirth;
            oldestPerson = person;
           } 
      } 

      else {
         person.yearOfDeath = yyyy;
         if ((person.yearOfDeath - person.yearOfBirth) > oldest){
            oldest = person.yearOfDeath - person.yearOfBirth;
            oldestPerson = person;
           }
      }

   });

     console.table(oldestPerson);
     console.table(arr);
}



const people = [
      {
        name: 'Carly',
        yearOfBirth: 1066,
      },
      {
        name: 'Ray',
        yearOfBirth: 1962,
        yearOfDeath: 2011
      },
      {
        name: 'Jane',
        yearOfBirth: 1912,
        yearOfDeath: 1941
      },
    ];

findTheOldest(people);

需要任何帮助吗？

Answer 1

我这样做是这样的：

const people = [
      {
        name: 'Carly',
        yearOfBirth: 1066,
      },
      {
        name: 'Ray',
        yearOfBirth: 1962,
        yearOfDeath: 2011
      },
      {
        name: 'Jane',
        yearOfBirth: 1912,
        yearOfDeath: 1941
      },
];

function findOldest(arr){
   let ages = people.map(el => {
      let age = el.yearOfDeath == undefined ? new Date().getFullYear() - el.yearOfBirth : el.yearOfDeath - el.yearOfBirth;
      return age;
   })
   let maxAge = Math.max(...ages);
   let index = ages.indexOf(maxAge);
   return arr[index];
}

console.log(findOldest(people));

Answer 2

如果将reduce替换为for循环，则可以使用。不知道为什么需要在那里打reduce。

let findTheOldest = function(arr) {
    var oldest = 0;
    var oldestPerson = {};
    var today = new Date();
    var yyyy = today.getFullYear();

    for (let i in arr) {
       const person = arr[i];
       if (person.yearOfDeath){
           if ((person.yearOfDeath - person.yearOfBirth) > oldest){
              oldest = person.yearOfDeath - person.yearOfBirth;
              oldestPerson = person;
             } 
        } 

        else {
           person.yearOfDeath = yyyy;
           if ((person.yearOfDeath - person.yearOfBirth) > oldest){
              oldest = person.yearOfDeath - person.yearOfBirth;
              oldestPerson = person;
             }
        }
    }
    
    return oldestPerson;
}



const people = [
      {
        name: 'Carly',
        yearOfBirth: 1066,
      },
      {
        name: 'Ray',
        yearOfBirth: 1962,
        yearOfDeath: 2011
      },
      {
        name: 'Jane',
        yearOfBirth: 1912,
        yearOfDeath: 1941
      },
    ];

const oldest = findTheOldest(people);

console.log(oldest); // shows {name: "Carly", yearOfBirth: 1066}

请注意，您正在修改原始数组元素（设置yearOfDeath）。如果要避免这种情况，请直接与该人还活着时的整个年度进行比较，而不是先将其设置为该对象。

稍微改进一下代码，这就是我在这里所做的：

if ((person.yearOfDeath || currentYear) - person.yearOfBirth > oldest)->如果yearOfDeath是undefined，将使用当前年份进行比较。

我还应用了reduce来遍历所有元素，假设您说这实际上是必需的。我在那里使用了带有两个蓄电池的物体。另外，请检查您是否也需要对其进行初始化。

let findTheOldest = function(arr) {
    const currentYear = new Date().getFullYear();
    const result = arr.reduce(({ oldest, oldestPerson }, person) => {
       if ((person.yearOfDeath || currentYear) - person.yearOfBirth > oldest)         {
          oldest = (person.yearOfDeath || currentYear) - person.yearOfBirth;
          oldestPerson = person;
        }
        
        return { oldest, oldestPerson };

    }, { oldest: 0, oldestPerson: {} });
    
    return result.oldestPerson;
}



const people = [
      {
        name: 'Carly',
        yearOfBirth: 1066,
      },
      {
        name: 'Ray',
        yearOfBirth: 1962,
        yearOfDeath: 2011
      },
      {
        name: 'Jane',
        yearOfBirth: 1912,
        yearOfDeath: 1941
      },
    ];

const oldest = findTheOldest(people);

console.log(oldest); // shows {name: "Carly", yearOfBirth: 1066}

Answer 3

此处最好使用.sort()而不是.reduce()。按yearOfDeath - yearOfBirth降序排序，并返回已排序数组的第一个元素：

let findTheOldest = function(arr) {
  var oldest = 0;
  var oldestPerson = [];
  var today = new Date();
  var yyyy = today.getFullYear();


  oldestPerson = arr.sort((personA, personB) => {
    if (personA.yearOfDeath && personB.yearOfDeath) {
      return (personA.yearOfDeath - personA.yearOfBirth) < (personB.yearOfDeath - personB.yearOfBirth) ? 1 : -1;
      }
    else {
    if (!personA.yearOfDeath) personA.yearOfDeath = yyyy;
    if (!personB.yearOfDeath) personB.yearOfDeath = yyyy;
    return (personA.yearOfDeath - personA.yearOfBirth) < (personB.yearOfDeath - personB.yearOfBirth) ? 1 : -1;
    }
  })[0];

  console.log(oldestPerson); //logs the Carly object
  console.log(oldestPerson.name); //logs "Carly"

}

检查对象数组中是否存在键/值对-Javascript

3 个答案: