function GetAllRepeatingCharacters(str) {
const repeating = {};
for (const ch of str) {
repeating[ch] = (repeating[ch] || 0) + 1;
}
return Object.entries(repeating).filter(ch => ch[1] > 1).map(ch => ch[0]);
}
const s = "java c c++ csharp node.js php python";
console.log(GetAllRepeatingCharacters(s));
/*
run:
[
'j', 'a', ' ', 'c',
'+', 's', 'h', 'p',
'n', 'o'
]
*/