let currencyList = {..... } // the full list as provided in this repo

console.log(currencyList.USD);

//======================
// output
//======================
{
  name: 'United States Dollar',
  demonym: 'US',
  majorSingle: 'Dollar',
  majorPlural: 'Dollars',
  ISOnum: 840,
  symbol: '$',
  symbolNative: '$',
  minorSingle: 'Cent',
  minorPlural: 'Cents',
  ISOdigits: 2,
  decimals: 2,
  numToBasic: 100
}

let MyCurrecy = "USD";
let value = 3;
let demonym = currencyList[MyCurrecy].demonym;

if (value >1) {
console.log("The value is "+value+" "+demonym + " " + currencyList[MyCurrecy].majorPlural);
} else {
console.log("The value is "+value+" "+demonym + " " + currencyList[MyCurrecy].majorSingle);
}


//======================
\\ output
//======================

The value is 3 US Dollars

let MyCurrecy = "INR";
let value = 3;

if (value >1) {
console.log("The value is "+value+" "+ currencyList[MyCurrecy].majorPlural);
} else {
console.log("The value is "+value+" "+ currencyList[MyCurrecy].majorSingle);
}

//======================
\\ output
//======================

The value is 3 Rupees