Your question could possibly be addressed by using a relatively recent feature in JavaScript: map objects.
Note that when you have an array of indeterminate length where each element is itself an array that is two elements long, you can convert the outer array into a map object instead of just a plain object. e.g. const newMapObj = new Map([['a', 1], ['b', 2]]);. Entering that into a terminal and then checking console.log(newMapObj) produces the following: Map { 'a' => 1, 'b' => 2 }. In your example, you could do this with each of your two list elements/store items, i.e. you would end up with an array of 2 map objects.
Such map objects have some convenient features, such as get and has. Some people also find them frustrating because of e.g. a lack of some helpful methods used with, say, arrays, like, um, well, the map method. (Note that the map method on arrays and the map/Map data object type are two completely different things. I know, it's confusing.)
The code snippet below creates an array of such map objects, one for each outer array element (i.e. one for each store 'item'), with one simple line:
const newResult = list.map(a => new Map(a));
Unfortunately, at this point in time at least, the code snippet tool here on Stack Exchange doesn't allow us to simply show the map object using console.log the way you can with, say, a plain object or an array. As a 2nd best substitute, the code snippet below logs out some of the results of using the map objects, just to demonstrate that the map objects were in fact created.
When I do the same thing in a Mac terminal (i.e. define list as the nested arrays in your question and then calculate newResult as above), console.log(newResult) shows the following:
[ Map { 'itemCode' => 1, 'item' => 'Pen', 'cashier' => 'Sam' },
Map { 'itemCode' => 2, 'item' => 'Eraser', 'cashier' => 'Kim' } ]
In other words, it is an array of map objects instead of an array of objects.
If you're interested in this recent JavaScript feature, you should check out the MDN documentation on the Map data object.
Whether you really want to use map objects or plain objects depends on your use case. The MDN documentation linked above has a short section to help you determine whether you want to use map objects or plain objects.
const list = [
[
['itemCode', 1],
['item', 'Pen'],
['cashier', 'Sam']
],
[
['itemCode', 2],
['item', 'Eraser'],
['cashier', 'Kim']
]
];
const newResult = list.map(a => new Map(a));
console.log('The name for the 1st item is:', newResult[0].get('item'));
console.log('The cashier for the 2nd item is:', newResult[1].get('cashier'));
