Compare 2 JavaScript objects and move data based on condition

Question

I have a function called syncWithPreviousDay that receives below array of object as a propery.

jsonObj

[
    {
        "Position": "1",
        "TrackName": "Rocket",
        "URL": "https://domain.local/nbs678"
    },
    {
        "Position": "2",
        "TrackName": "Dueling banjos",
        "URL": "https://domain.local/asd456"
    },
    {
        "Position": "3",
        "TrackName": "One hit wonder",
        "URL": "https://domain.local/xyz123"
    }
]

Inside this function I need compare the key URL with another array of objects from my database that has the same key pairs and wherever there is a match, move the keys Position and CustomKey to new key PreviousPosition and CustomKey in the data.chart array. If there is no match, create a null value for both keys.

const syncWithPreviousDay = (jsonObj) => {

const data = {
    date: config.dateToday,
    chart: jsonObj
}

dbService.getDate(config.yesterday)
    .then( result => {
        console.log(result.chart)
    })
}

Result from the console.log looks like this:

[
    {
        "Position": "1",
        "TrackName": "One hit wonder",
        "URL": "https://domain.local/xyz123",
        "CustomKey": "x"
    },
    {
        "Position": "2",
        "TrackName": "Awesome old song",
        "URL": "https://domain.local/123qwe",
        "CustomKey": "y"
    },
    {
        "Position": "3",
        "TrackName": "Dueling banjos",
        "URL": "https://domain.local/asd456",
        "CustomKey": null
    }
]

So my desired data.chart should somehow look like this:

[
    {
        "Position": "1",
        "TrackName": "Rocket",
        "URL": "https://domain.local/nbs678",
        "PreviousPosition": null,
        "CustomKey": null
    },
    {
        "Position": "2",
        "TrackName": "Dueling banjos",
        "URL": "https://domain.local/asd456",
        "PreviousPosition": "3",
        "CustomKey": null
    },
    {
        "Position": "3",
        "TrackName": "One hit wonder",
        "URL": "https://domain.local/xyz123",
        "PreviousPosition": "1",
        "CustomKey": "x"
    }
]

How can this be done?

Jasdeep Singh · Accepted Answer · 2020-03-30 09:21:41Z

2

You can simply do it by iterating a loop and matching if a particular element exist in database array or not. If values exist then add the required values else add null values.

I have provided the logic to you, you can use it inside the function or any place you need it.

const localArr = [
    {
        "Position": "1",
        "TrackName": "Rocket",
        "URL": "https://domain.local/nbs678"
    },
    {
        "Position": "2",
        "TrackName": "Dueling banjos",
        "URL": "https://domain.local/asd456"
    },
    {
        "Position": "3",
        "TrackName": "One hit wonder",
        "URL": "https://domain.local/xyz123"
    }
];

const dbArray = [
    {
        "Position": "1",
        "TrackName": "One hit wonder",
        "URL": "https://domain.local/xyz123",
        "CustomKey": "x"
    },
    {
        "Position": "2",
        "TrackName": "Awesome old song",
        "URL": "https://domain.local/123qwe",
        "CustomKey": "y"
    },
    {
        "Position": "3",
        "TrackName": "Dueling banjos",
        "URL": "https://domain.local/asd456",
        "CustomKey": null
    }
];

for (const element of localArr) {
  const index = dbArray.findIndex(item => item.URL === element.URL);
  if (index !== -1) {
    element.PreviousPosition = dbArray[index].Position;
    element.CustomKey = dbArray[index].CustomKey;
  } else {
    element.PreviousPosition = null;
    element.CustomKey = null;
  }
}

console.log(localArr)

answered Mar 30, 2020 at 9:21

Jasdeep Singh

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1 Comment

Dave Over a year ago

Thank you very much! I was able to make it work exactly as I wanted it to. All the best

Abhishek Kulkarni · Accepted Answer · 2020-03-30 09:24:35Z

0

Assuming your objects are obj1 and obj2 :

       obj1.map(function (item_1) {
                obj2 = obj2.map(function (item_2) {
                   if(item_1.URL == item_2.URL){
                       item_2['PreviousPosition']=item_1['Position'];
                       item_2['CustomKey']=item_1['CustomKey'];
                   }else{
                       item_2['PreviousPosition']=null;
                       item_2['CustomKey']=null;
                   }
                   return item_2
                });
            });

answered Mar 30, 2020 at 9:24

Abhishek Kulkarni

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