JSFiddle - React, Tailwind, and code Playground

by Gaurav Gandhi

HTML

<pre id="resultPane"></pre>

JavaScript

CurrentDataFormat = [{
        "Id": 17,
        "code": "123",
        "cityName": "Los Angeles",
        "startDate": "1/20/2016",
        "endDate": "1/20/2016"
    },

    {
        "Id": 18,
        "code": "456",
        "cityName": "Chicago",
        "startDate": "1/22/2016",
        "endDate": "1/25/2016"
    },

    {
        "Id": 19,
        "code": "789",
        "cityName": "Los Angeles",
        "startDate": "1/13/2016",
        "endDate": "1/21/2016"
    }
]


var refinedArray = {};

for (i = 0; i < CurrentDataFormat.length; i++) {
    refinedArray[CurrentDataFormat[i].cityName] = refinedArray[CurrentDataFormat[i].cityName] ? refinedArray[CurrentDataFormat[i].cityName] : {};

    refinedArray[CurrentDataFormat[i].cityName].name = CurrentDataFormat[i].cityName;

    refinedArray[CurrentDataFormat[i].cityName].CityData = refinedArray[CurrentDataFormat[i].cityName].CityData ? refinedArray[CurrentDataFormat[i].cityName].CityData : [];
    refinedArray[CurrentDataFormat[i].cityName].CityData.push({
        "Id": CurrentDataFormat[i].Id,
        "code": CurrentDataFormat[i].code,
        "startDate": CurrentDataFormat[i].startDate,
        "endDate": CurrentDataFormat[i].endDate
    });
}

var ExpectedDataFormat = [];

for (singleCityName in refinedArray){
	ExpectedDataFormat.push({'name' : refinedArray[singleCityName].name, 'CityData' : refinedArray[singleCityName].CityData});
};

console.log(ExpectedDataFormat);
document.getElementById("resultPane").innerHTML = JSON.stringify(ExpectedDataFormat, undefined, 2);;