通过数组中的多个属性对对象进行分组，然后对其值求和

通过数组中的多个属性对对象进行分组，然后对其值求和

将Array＃reduce与帮助器对象一起使用可以对相似的对象进行分组。对于每个对象，检查合并的

shape

和是否

color

存在于帮助器中。如果不是，请使用Object＃assign添加到帮助器中以创建对象的副本，然后将其压入数组。如果是这样，请将其值添加到

used

和

instances

。

var arr = [{"shape":"square","color":"red","used":1,"instances":1},{"shape":"square","color":"red","used":2,"instances":1},{"shape":"circle","color":"blue","used":0,"instances":0},{"shape":"square","color":"blue","used":4,"instances":4},{"shape":"circle","color":"red","used":1,"instances":1},{"shape":"circle","color":"red","used":1,"instances":0},{"shape":"square","color":"blue","used":4,"instances":5},{"shape":"square","color":"red","used":2,"instances":1}];var helper = {};var result = arr.reduce(function(r, o) {  var key = o.shape + '-' + o.color;  if(!helper[key]) {    helper[key] = Object.assign({}, o); // create a copy of o    r.push(helper[key]);  } else {    helper[key].used += o.used;    helper[key].instances += o.instances;  }  return r;}, []);console.log(result);

如果你可以使用ES6，您可以使用地图收集的值，然后将其转换回一个数组蔓延的地图＃值：

const arr = [{"shape":"square","color":"red","used":1,"instances":1},{"shape":"square","color":"red","used":2,"instances":1},{"shape":"circle","color":"blue","used":0,"instances":0},{"shape":"square","color":"blue","used":4,"instances":4},{"shape":"circle","color":"red","used":1,"instances":1},{"shape":"circle","color":"red","used":1,"instances":0},{"shape":"square","color":"blue","used":4,"instances":5},{"shape":"square","color":"red","used":2,"instances":1}];const result = [...arr.reduce((r, o) => {  const key = o.shape + '-' + o.color;  const item = r.get(key) || Object.assign({}, o, {    used: 0,    instances: 0  });  item.used += o.used;  item.instances += o.instances;  return r.set(key, item);}, new Map).values()];console.log(result);