Replace elements in an object and array?

Question

If I draw from the object y, for example 'JPY 20, USD 20', I want to replace the USD and JPY abbreviation with the extended name DOLLAR and JEN. It has to look like this: 'JPY 20, USD 20' replace to 'JEN 20, DOLLAR 20'

var x = {
 'U': 'DOLLAR',
 'J': 'JEN',
 'E': 'EURO'
};
var y = [
 'U 50',
 'J 20, U 20',
 'E 20, J 10'
];
var z = y[Math.floor(Math.random() * y.length)]; //example 'JPY 20, USD 20'
for(var key in x) {
 var c = new RegExp({key}, "g");
 z = z.replace(key, x[key]); 
 console.log(z); //It should looks like //'JEN 20, DOLLAR 20'
} 

var x = { U: 'DOLLAR', J: 'JEN', E: 'EURO' },
 y = ['U 50', 'J 20, U 20', 'E 20, J 10'],
 z = y[Math.floor(Math.random() * y.length)],
 key,
 regex;
for (key in x) {
 regex = new RegExp(key, "g");
 z = z.replace(regex, x[key]); 
} 
console.log(z);

Answer 1

You coudl take all strings for replacement and join it with pipe for aleternative searches and replace with the new value.

var array = ['U 50', 'J 20, U 20', 'E 20, J 10'],
 replacements = { U: 'DOLLAR', J: 'JEN', E: 'EURO' },
 string = array[Math.floor(Math.random() * array.length)],
 regex = new RegExp(Object.keys(replacements).join('|'), "g");
string = string.replace(regex, key => replacements[key]); 
console.log(string);

• Umbro: How should I set regex if var x = { U: 'DOLLAR', J: 'JEN', E: 'EURO' }, y = ['U 50', 'J 20, U 20', 'E 20, J 10']; Random 'J 20, U 20'; console.log return "EURO 20, JEURON 10"
• Nina Scholz: just take the same code. the lenght of the replacement strings is not importent unless they are unique.
• Umbro: console.log return JEURON instead JEN