How to sum certain index in an array in javascript

Question

Let's say I have an array.

[ '219_1_undefined', '244_1_undefined', '248_1_20///179+25///153', '221_6_undefined' ]

Breakdown for a single item in the array goes by 219_1_undefined basically is 219 is product_id, 1 is the quantity and undefined is the product_options I'm storing these information in local storage. Now I have a new item that needs to be added to the cart, but this product is already in cart so I want to add the quantity alone (middle value). So I want to add 219_1_undefined again to the existing array. Now the array will be look like this.

[ '219_1_undefined', '244_1_undefined', '248_1_20///179+25///153', '221_6_undefined', '219_1_undefined' ]

My problem is I don't know how to add the middle value(quantity) of the same product and get result like

[ '244_1_undefined', '248_1_20///179+25///153', '221_6_undefined', '219_2_undefined' ]

Below is the code I tried

let pid = 219;
let qty = 1;
let params = "undefined";

let string = '219_1_undefined|244|1_undefined|248_1_20///179+25///153|221_1_undefined';

let items = string.split('|');

 let nItem = pid+'_'+qty+'_'+params;
 let mx = items;
 mx = mx.filter(function (item) {
  return item.indexOf(pid+'_') !== 0;
  });
 mx.push(nItem);
 var result = mx.toLocaleString();
 let nresult = result.split(',').join('|');
      
 console.log(nresult);

No matter what I do I still get the wrong output.

That's a... strange format. Why don't you use an array of objects ({ id: ..., options: ..., quantity: ... })? — Andreas
– Andreas, Commented Sep 22, 2021 at 13:16
Because I'm storing this array in local storage as string that's why — Viira
– Viira, Commented Sep 22, 2021 at 13:16
You already have to use JSON.parse() so throw in an additional JSON.stringify() and work with something more useful (like an array of objects) — Andreas
– Andreas, Commented Sep 22, 2021 at 13:18
Man I get it, this is my junior dev's issue the manager has assigned this to me This exact same format is being used in over for 6 - 7 pages that's very cumbersome for me to do that — Viira
– Viira, Commented Sep 22, 2021 at 13:19

Mamun · Accepted Answer · 2021-09-22 13:57:27Z

1

You can try getting the index using Array.prototype.findIndex() and update the array item using that index:

let pid = 219;
let qty = 1;
let params = "undefined";

let items = ['219_1_undefined', '244_1_undefined', '248_1_20///179+25///153', '221_1_undefined'];

//get the index of the item from the array by matching the id
let index = items.findIndex(p => p.split('_')[0] == pid);
//check if any item is exist in the array
if(index > -1){
  //using the index update the item in the array with the new value
  items[index] = pid + '_' + (+items[index].split('_')[1] + qty) + '_' + params;
}
else{
  //push new item to the arry
  items.push(pid + '_' + qty + '_' + params);
}

console.log(items);

edited Sep 22, 2021 at 13:57

answered Sep 22, 2021 at 13:21

Mamun

69k9 gold badges51 silver badges62 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Husman · Accepted Answer · 2021-09-22 13:44:31Z

0

let pid = 219;
let qty = 1;
let params = "undefined";

let string = '219_1_undefined|244|1_undefined|248_1_20///179+25///153|221_1_undefined';
let items = string.split('|');
let i = 0;

for(; i < items.length; i++) {
  let temp = items[i].split('_');
  if (temp[0] == pid && temp[2] == params) {
    qty = parseInt(qty) + parseInt(temp[1]);
    break;
  }
}

items[i] = `${pid}_${qty}_${params}`;
string = items.join('|');

I tested this and it appears to work.The if statement compares botht he ID and param, but obviously you can only have it check the ID if you want.

answered Sep 22, 2021 at 13:44

Husman

6,93910 gold badges32 silver badges48 bronze badges

Collectives™ on Stack Overflow

How to sum certain index in an array in javascript

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related