An array of nested objects, attributes to be the same weight, a property value corresponding to the merged

 

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

 

 

 

 Want to get the format

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

Implementation process

Function mergeArr (MRA) {
     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
    }

transfer

mergeArr (date)