infinite algorithm. javascript

Question

i'm pretty new to js. i'm sorry if this sounds dumb.I have such an algorithm for javascript. when executed, it loops. Why? What is his mistake? I have such source data enter image description here

let incomesArray = [];
incomesArray[0] = {

    income_id: incomeList[0].id,
    worker_id: incomeList[0].worker_id,
    worker_surname: incomeList[0].worker_surname,
    worker_name: incomeList[0].worker_name,
    incomeList: [
        {
        provider_name: incomeList[0].provider_name,
        product_category: incomeList[0].product_category_name,
        product_name: incomeList[0].product_name,
        product_count: incomeList[0].product_count,
        purchase_price: incomeList[0].purchase_price
        }
    ],
    incomeDate: incomeList[0].date,
    total: incomeList[0].total
}

if(incomesArray.length > 0 ){
  for(let i = 1; i < incomeList.length; i++) {
    for(let j = 0; j < incomesArray.length; j++){
      if(incomeList[i].id == incomesArray[j].id){
          for(let k = 0; k < incomesArray[j].incomeList.length; k++){
                  incomesArray[j].incomeList.push({
                      provider_name: incomeList[i].provider_name,
                      product_category: 
                      incomeList[i].product_category_name,
                      product_name: incomeList[i].product_name,
                      product_count: incomeList[i].product_count,
                      purchase_price: incomeList[i].purchase_price
                   })
               }
      } else if (incomesArray[j].id !== incomeList[i].id) {
        incomesArray.push({
            income_id: incomeList[i].id,
            worker_id: incomeList[i].worker_id,
            worker_surname: incomeList[i].worker_surname,
            worker_name: incomeList[i].worker_name,
            incomeList: [
                {
                provider_name: incomeList[i].provider_name,
                product_category: incomeList[i].product_category_name,
                product_name: incomeList[i].product_name,
                product_count: incomeList[i].product_count,
                purchase_price: incomeList[i].purchase_price
                }
            ],
            incomeDate: incomeList[i].date,
            total: incomeList[i].total
        })
      }
    }
  }                                            
}

I will be grateful for any help or hint.

Thomas · Accepted Answer · 2020-05-25 01:21:35Z

It's your else part that causes the problem. For every item in incomesArray that has a different id than the item in incomeList you add another entry to incomesArray; while you're iterating over that array. Like this gif:

Extending the track while you're driving on it.

Second, your comparison: if(incomeList[i].id == incomesArray[j].id) but incomesArray[j] has no id, only a income_id, so you'll always run into the else part where you add more items to incomesArray.

I've restructured your code a bit:

const incomesArray = [];

for (const row of incomeList) {
  let target = incomesArray.find(item => item.income_id === row.id);

  if (!target) {
    incomesArray.push(target = {
      income_id: row.id,
      worker_id: row.worker_id,
      worker_surname: row.worker_surname,
      worker_name: row.worker_name,
      incomeList: [],
      incomeDate: row.date,
      total: row.total
    });
  }

  target.incomeList.push({
    provider_name: row.provider_name,
    product_category: row.product_category_name,
    product_name: row.product_name,
    product_count: row.product_count,
    purchase_price: row.purchase_price
  });
}

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