Doing group by like in JavaScript using the reduce function, see:

var countriesSubscription = [

{ Exchange: 'ASX', CountryId: 1, ExchangeRate: 1, CountryName: "Australia", Code: "AU", CurrencyForeign: "AUD", CurrencyLocal: "AUD", IsSubscribed: true, PriceLocal: 15.75, PriceForeign: null, DataType: "ClickToRefresh" },

{ Exchange: 'ASX', CountryId: 2, ExchangeRate: 1.01, CountryName: "Canada", Code: "CAN", CurrencyForeign: "CAD", CurrencyLocal: "AUD", IsSubscribed: false, PriceLocal: null, PriceForeign: null, DataType: "" },

{ Exchange: 'ASX', CountryId: 3, ExchangeRate: 5.78, CountryName: "Hong Kong", Code: "HKG", CurrencyForeign: "HKD", CurrencyLocal: "AUD", IsSubscribed: false, PriceLocal: null, PriceForeign: null, DataType: "" },

{ Exchange: 'CHIX', CountryId: 4, ExchangeRate: 0.74, CountryName: "US", Code: "USA", CurrencyForeign: "USD", CurrencyLocal: "AUD", IsSubscribed: true, PriceLocal: null, PriceForeign: null, DataType: "" },

{ Exchange: 'ASX', CountryId: 5, ExchangeRate: 0.67, CountryName: "France", Code: "FRA", CurrencyForeign: "EUR", CurrencyLocal: "AUD", IsSubscribed: false, PriceLocal: null, PriceForeign: null, DataType: "" },

{ Exchange: 'CHIX', CountryId: 6, ExchangeRate: 1.37, CountryName: "Switzerland", Code: "CHE", CurrencyForeign: "CHF", CurrencyLocal: "AUD", IsSubscribed: true, PriceLocal: null, PriceForeign: null, DataType: "" },

{ Exchange: 'ASX', CountryId: 7, ExchangeRate: 0.73, CountryName: "Belgium", Code: "BEL", CurrencyForeign: "EUR", CurrencyLocal: "AUD", IsSubscribed: false, PriceLocal: null, PriceForeign: null, DataType: "" },

];

// **** Array to group by Exchange ****

var groupByCurrency = countriesSubscription.reduce(function(all, item, index){

all[item.Exchange].push(item);

return all;

}, {CHIX:[], ASX:[]});

groupByCurrency.ASX.forEach(function(item){

console.log(item);

})

groupByCurrency.CHIX.forEach(function(item){

console.log(item);

})

output:

CountryId: 5, ExchangeRate: 0.67, CountryName: 'France', Code: 'FRA', CurrencyForeign: 'EUR', CurrencyLocal: 'AUD', IsSubscribed: false, PriceLocal: null, PriceForeign: null, DataType: '' } { Exchange: 'ASX', CountryId: 7, ExchangeRate: 0.73, CountryName: 'Belgium', Code: 'BEL', CurrencyForeign: 'EUR', CurrencyLocal: 'AUD', IsSubscribed: false, PriceLocal: null, PriceForeign: null, DataType: '' }

{ Exchange: 'CHIX', CountryId: 4, ExchangeRate: 0.74, CountryName: 'US', Code: 'USA', CurrencyForeign: 'USD', CurrencyLocal: 'AUD', IsSubscribed: true, PriceLocal: null, PriceForeign: null, DataType: '' } { Exchange: 'CHIX', CountryId: 6, ExchangeRate: 1.37, CountryName: 'Switzerland', Code: 'CHE', CurrencyForeign: 'CHF', CurrencyLocal: 'AUD', IsSubscribed: true, PriceLocal: null, PriceForeign: null, DataType: '' }