updateInventory.js

const updateInventory = (arr1, arr2) => {

    const upInv = arr1.slice();

    for (const newItem of arr2) {

        let found = false;

        for (const curItem of arr1) {
            

            if (curItem[1] === newItem[1]) {
                found = true;
                curItem[0] += newItem[0];
                break;
            }

        }

        if (!found) {
            // console.log("not found", newItem[1]);
            upInv.push(newItem);
        }
    }

    upInv.sort((item1, item2) => {
        return (item1[1]<item2[1]) 
            ? -1 
            : (item1[1]>item2[1])
            ? 1
            : 0
    });

    return upInv;
} 

// Example inventory lists
let curInv = [
    [21, "Bowling Ball"],
    [2, "Dirty Sock"],
    [1, "Hair Pin"],
    [5, "Microphone"]
];

let newInv = [
    [2, "Hair Pin"],
    [3, "Half-Eaten Apple"],
    [67, "Bowling Ball"],
    [7, "Toothpaste"]
];

console.log(updateInventory(curInv, newInv));