数组嵌套对象，将相同属性去重，对应的某个属性值合并

var data = [
    { province: 1, index:1},
    { province: 2, index:3},
    { province: 1, index:3},
    { province: 2, index:2}
]

 想要得到的格式

{ province: 1, index:4},
{ province: 2, index:5}

实现过程

方法一：

console.log(editArr(data, 'province', 'index'));

function editArr(data, repeat, merge){
    // repeat: 去重的key
    // merge： 合并的key
    var currArr = []
    var newArr = []
    data.forEach((item,i)=>{
        if(currArr.indexOf(data[i][repeat]) == -1){
            newArr.push({
                [repeat]: data[i][repeat],
                [merge]: data[i][merge]
            })
            currArr.push(data[i][repeat])
        }else{
            newArr.forEach(subItem=>{
                if(subItem[repeat] == data[i][repeat]){
                    subItem[merge] += data[i][merge]
                }
            })
        }
            
    })
    return newArr
}

方法二：

function mergeArr(arr){
    var newArr=[];
        arr.forEach(item=>{
        var dataItem =item
            if(newArr.length>0){
                var filterValue = newArr.filter(v=>{
                   return v.province == dataItem.province
                })
                if(filterValue.length>0){
                    newArr.forEach(n=>{
                       if( n.province ==filterValue[0].province){
                           n.index =  Number(filterValue[0].index) + Number(dataItem.index)
                       } 
                    })
                }else{
                    newArr.push(dataItem)
                }
            }else{
                newArr.push(dataItem)
            }
    
    })
    return newArr
    }

调用

mergeArr(data)