The solution to the free code camp challenge called "Record Collection", from the JavaScript Algorithms and Data Structures Course

FreeCodeCamp_record_collection_sol.js

function updateRecords(records, id, prop, value) {
  var record = records[id];
  if(prop !== "tracks" && value !== "") {
    record[prop] = value;
  } else if (value === ""){
    delete record[prop];
  } else if (prop == "tracks") {
    if(record.hasOwnProperty("tracks") === false) {
      record["tracks"] = [];
      record["tracks"].push(value);
    } else {
      record["tracks"].push(value);
    }
  }
  return records;
}