To apply for my dirty code(2)

let personalAggregate = (data) => {

    let totalNumOfUse = data.length;
    let reward = 0;
    let userArr = [];
    let filteredData = [];
    let peopleInfo = [];
    let numOfUse = 0;

    for(let i in data) {

        let userId = data[i].userId;
        userArr.push(userId);

    }

    let filteredId = userArr.filter((item, index) => userArr.indexOf(item) === index);

    for(let i in filteredId) {
        
        filteredData = data.filter(item => item.userId === filteredId[i]);
        
        peopleInfo.push(filteredData);
        
        for(let j in filteredData) {
            
            let result = filteredData[j].result.by;
            // console.log(result);
            
            reward += peopleInfo[i][j].result.by;
            // console.log(reward);            
            let obj = { [filteredData[j].userId] : filteredData[j].result.by }
            console.log(obj)
        }
    }    

    // return peopleInfo;
}

personalAggregate(dummyData);

On second day, I fixed filteredData code with indexOf function and push.

Even though, It looks dirty still because I used meaningless variables and Two–dimensional array.