JSON Serialization into Local Storage.js

//https://stackoverflow.com/questions/79591547/unknown-json-stringify-issue

if (localStorage.balances == undefined) {
    localStorage.setItem('balances', '{"ffdbddfaae": "0"}') // initialize balance so JSON doesn't error out
}
let balances = JSON.parse(localStorage.balances) // convert string to JSON object for further changes

let addToBalance = function(value, id) {
    let key = id.replace(/[0-9]/g, '') // convert alphaumerical id string to only letters to not cause errors when using balances.(id)
    if (key in balances) { // convert alphaumerical id string to only letters to not cause errors when using balances.(id) and check if id exists in balance object
        balances[key] += value
    } else {
        balances[key] = value
    }
    localStorage.setItem("balances", JSON.stringify(balances))
}
addToBalance(100, "ffdbddfaae")
addToBalance(69, "foobarid")