How to get object properties from max value property in a json object

Question

I have the following array of objects. I need to obtain the properties of the item which has the highest MoveCount. I have a function which returns me only the MoveCount. But I want to get the value of Latitude and Longitude as well.

The function I used is as follows:

var res = Math.max.apply(Math,movers.map(function(o){ return o.MoveCount, o.Latitude, o.Longitude;})) alert('Max y = ' + res);

Objects:

var movers = [{"MoveCount":3,"DepartureCountryCode":"MG","Latitude":-18.766947,"Longitude":46.869107}, {"MoveCount":2,"DepartureCountryCode":"MU","Latitude":-20.348404,"Longitude":57.552152}, {"MoveCount":4,"DepartureCountryCode":"ZA","Latitude":-30.559482,"Longitude":22.937506}];

That is an array of objects, not JSON. JSON is a text-based data-interchange format. It may have been derived from a string of JSON, but in its current form it is not JSON. — Useless Code
– Useless Code, Commented Feb 23, 2018 at 6:03

Useless Code · Accepted Answer · 2018-02-23 06:44:22Z

You can use a custom sort function based on MoveCount. This would retain the entire object as it is.

var movers = [ { "MoveCount":3, "DepartureCountryCode":"MG", "Latitude":-18.766947, "Longitude":46.869107 }, { "MoveCount":2, "DepartureCountryCode":"MU", "Latitude":-20.348404, "Longitude":57.552152 }, { "MoveCount":4, "DepartureCountryCode":"ZA", "Latitude":-30.559482, "Longitude":22.937506 } ]; movers.sort(function(a,b){ return b.MoveCount - a.MoveCount; }); var highestMoveCount = movers[0]; // get the item with the highest MoveCount console.log(highestMoveCount);

The above code returns an array sorted descending by MoveCount.

Sorting is one way of finding the highest count, but would be an inefficient way of doing it, particularly if you have a large dataset.
@jones Once the array is sorted, the item with the highest MoveCount is the first item in the array, so you would access it via movers[0]. So, to get the latitude, you would use movers[0].Latitude, etc.

Suren Srapyan · Accepted Answer · 2018-02-23 05:56:56Z

Sort the array, use map function to change the outcoming objects and get the first item from the sorted array.

var movers = [ { "MoveCount": 3, "DepartureCountryCode": "MG", "Latitude": -18.766947, "Longitude": 46.869107 }, { "MoveCount": 2, "DepartureCountryCode": "MU", "Latitude": -20.348404, "Longitude": 57.552152 }, { "MoveCount": 4, "DepartureCountryCode": "ZA", "Latitude": -30.559482, "Longitude": 22.937506 }]; const highest = movers.sort((a,b) => b.MoveCount - a.MoveCount) .map(({MoveCount, Latitude, Longitude}) => ({MoveCount, Latitude, Longitude}))[0]; console.log(highest);

Jonas Wilms · Accepted Answer · 2018-02-23 06:17:35Z

You might reduce the movers by always taking the bigger one:

 const biggest = movers.reduce((max, mover) => max.MoveCount > mover.MoveCount ? max : mover);

Prasanna · Accepted Answer · 2018-02-23 06:19:55Z

You can sort as others say , but that would take O(nlogn) complexity. Or you can just compare the highest value in O(n) complexity.

const movers = [{"MoveCount":3,"DepartureCountryCode":"MG","Latitude":-18.766947,"Longitude":46.869107}, {"MoveCount":2,"DepartureCountryCode":"MU","Latitude":-20.348404,"Longitude":57.552152}, {"MoveCount":4,"DepartureCountryCode":"ZA","Latitude":-30.559482,"Longitude":22.937506}] let highest = movers[0] for (let index=1; index<movers.length; index += 1) { let movObj = movers[index]; if (movObj.MoveCount > highest.MoveCount) { highest = movObj; } } console.log(highest) // if you only want certain fields const certainFieldsRes = ({MoveCount, Latitude, Longitude}) => ({ MoveCount, Latitude, Longitude }) console.log(certainFieldsRes(highest))

Useless Code · Accepted Answer · 2018-02-23 06:32:21Z

I'd probably use Array.prototype.reduce to traverse the array to find the item with the highest MoveCount.

let movers = [ { "MoveCount":3, "DepartureCountryCode":"MG", "Latitude":-18.766947, "Longitude":46.869107 }, { "MoveCount":2, "DepartureCountryCode":"MU", "Latitude":-20.348404, "Longitude":57.552152 }, { "MoveCount":4, "DepartureCountryCode":"ZA", "Latitude":-30.559482, "Longitude":22.937506 } ]; let getHighestMoveCount = function (arr) { let o = arr.reduce(function (accumulator, currentValue, currentIndex) { // if this is the first item, we have nothing to compare against, // just return this item if (currentIndex === 0) { return currentValue; } else { // if this item has a higher MoveCount than the current highest, // return it if (currentValue.MoveCount > accumulator.MoveCount) { return currentValue; } else { // otherwise return the current highest return accumulator; } } }); // return the object that has the highest MoveCount return o; // This returns the entire object, if you wanted a new object with // only the MoveCount Latitude and Longitude, you would do // this instead: // return {MoveCount: o.MoveCount, Latitude: o.Latitude, Longitude: o.Longitude}; }; console.log(getHighestMoveCount(movers));

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