javascript - 循环遍历对象数组并返回某些值的总和

Question

我有一个包含民意调查结果的对象数组，它看起来(例如)如下所示:

[
    {title: 'cat', optionid: 7, points: 1 }, 
    {title: 'cat', optionid: 7, points: 3 }, 
    {title: 'cat', optionid: 7, points: 1 }, 
    {title: 'dog', optionid: 8, points: 3 }, 
    {title: 'dog', optionid: 8, points: 2 }, 
    {title: 'dog', optionid: 8, points: 3 }, 
    {title: 'pig', optionid: 9, points: 2 }, 
    {title: 'pig', optionid: 9, points: 1 }, 
    {title: 'pig', optionid: 9, points: 1 }
]

基本上，我想循环遍历并总结每个选项ID/标题的分数。所以 cat = 5，dog = 8，pig = 4。有没有办法在 JavaScript 中做到这一点？到目前为止我所有的尝试都失败了。我是自学成才的，只是一个初学者，所以解决方案越简单越好。

Answer 1

我认为使用reduce是最好的方法。然而，对于像我这样的新手来说，这可能会令人困惑。所以这里有一个更直接的方法。希望这更容易理解。

var animals = [{title: 'cat', optionid: 7, points: 1 },
{title: 'cat', optionid: 7, points: 3 },
{title: 'cat', optionid: 7, points: 1 },
{title: 'dog', optionid: 8, points: 3 },
{title: 'dog', optionid: 8, points: 2 },
{title: 'dog', optionid: 8, points: 3 },
{title: 'pig', optionid: 9, points: 2 },
{title: 'pig', optionid: 9, points: 1 },
{title: 'pig', optionid: 9, points: 1 }];

// create new object to store results in
newObj = {};

// loop through animal objects
animals.forEach(function(animal){
 // check if animal type has already been added to newObj
 if(!newObj[animal.title]){
  // If it is the first time seeing this animal type
  // we need to add title and points to prevent errors
  newObj[animal.title] = {};
  newObj[animal.title]['points'] = 0;
 }
 // add animal points to newObj for that animal type.
 newObj[animal.title]['points'] += animal.points 
})
console.log(newObj)