遍历对象数组并返回某些值的总和

Question

我有一个包含轮询结果的对象数组，（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，我想遍历并总结每个optionid /标题的要点。 所以cat = 5，dog = 8，pig =4。在JavaScript中有没有办法做到这一点？ 到目前为止，我所有的尝试都以失败告终。 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

用reduce很容易

 var arr = [{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 }] var result = arr.reduce(function(acc, v) { acc[v.title] = (acc[v.title] || 0) + v.points return acc }, {}) console.log(result) 

Answer 2

使用减少

 let data = [ { 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 } ]; let result = data.reduce((re, obj) => { let index = re.map(o => o.optionid).indexOf(obj.optionid); index > -1 ? re[index].points += obj.points : re.push(obj); return re; }, []); console.log(result); 

Answer 3

我认为使用reduce是最好的方法。 但是，这对于像我这样的新手来说可能会造成混淆。 因此，这是一种更直接的方法。 希望这会更容易理解。

 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)