JavaScript Object Example: Record Collection

// Setup
var collection = {
    "2548":{
        "album": "Slippery When Wet",
        "artist": "Bon Jovi",
        "tracks": [
             "Let It Rock",
             "You Give Love a Bad Name"  
        ]
    },  
    "2468":{
        "album": "1999",
        "artist": "Prince",
        "tracks": [
            "1999",
            "Little Red Corvette"
        ]
    },  
    "1245":{
        "artist": "Robert Palmer",
        "tracks": []
    },
    "5439":{
        "album": "ABBA Gold"
    }
};

// Keep a copy of the collcection for tests
var collectionCopy = JSON.parse(JSON.stringify(collection));

// update 
function updateRecords(id,prop,value){
    if(value === ""){
        // 如果值为空, 则删除这个属性
        delete collection[id][prop];
    }else if (prop === "tracks"){
        collection[id][prop] = collection[id][prop] || []; 
        // 如果 track 存在, 则不做变动; 若不存在, 则创建一个track, 并将[]赋给它
        collection[id][prop].push(value); // 赋值 （添加至末端）   
    } else{
        collection[id][prop] = value;
    }

    return collection;
}    

// Alter values below to test your code
console.log(updateRecords(5439,"artist","ABBA")); 

LINK: https://www.youtube.com/watch?v=PkZNo7MFNFg&t=241s     2:03:00