1function removeDuplicateCharacters(string) {
2  return string
3    .split('')
4    .filter(function(item, pos, self) {
5      return self.indexOf(item) == pos;
6    })
7    .join('');
8}
9console.log(removeDuplicateCharacters('baraban'));

1String arr[] = {"12341234abc", "1234foo1234", "12121212", "111111111", "1a1212b123123c12341234d1234512345"};
2String regex = "(\\d+?)\\1";
3Pattern p = Pattern.compile(regex);
4for (String elem : arr) {
5    boolean noMatchFound = true;
6    Matcher matcher = p.matcher(elem);
7    while (matcher.find()) {
8        noMatchFound = false;
9        System.out.println(elem + " got repeated: " + matcher.group(1));
10    }
11    if (noMatchFound) {
12        System.out.println(elem + " has no repeation");
13    }
14}
15

1/* Time complexity of solution: O(n) */
2const getRepeatedChars = (str) => {
3 	const chars = {};
4    for (const char of str) {
5        chars[char] = (chars[char] || 0) + 1;
6    }
7    return Object.entries(chars).filter(char => char[1] > 1).map(char => char[0]);
8}
9
10getRepeatedChars("aabbkdndiccoekdczufnrz"); // ["a", "b", "c", "d", "k", "n", "z"]

1const text = 'abcda'.split('')
2text.some( (v, i, a) => {
3  return a.lastIndexOf(v) !== i
4}) // true

1const getRepeatedChars = (str) => {
2    let result = [];
3    str.map(each => {
4      let repeatedChars = 0;
5      for (let i = 0; i < each.length - 1; i++) {
6          if (each[i] === each[i + 1] && each[i] !== each[i - 1]) {
7            repeatedChars += 1;
8          }
9      }
10      
11        result.push(repeatedChars);
12    });
13
14    return result;
15};
16
17getRepeatedChars(["aaabbbkdnndicccoekdczufnrz", "awsfgds"]); // [4, 0]