const str = 'JavaScript C C++ TypeScript NodeJS';
let uppercase = str.replace(/[a-z]/g, '');
console.log(uppercase);
uppercase = str.replace(/[^A-Z]/g, '');
console.log(uppercase);
uppercase = str.match(/[A-Z]/g);
console.log(uppercase);
/*
run:
"JS C C++ TS NJS"
"JSCCTSNJS"
["J", "S", "C", "C", "T", "S", "N", "J", "S"]
*/