Showing Unique Characters In A String Only Once

I have a string with repeated letters. I want letters that are repeated more than once to show only once. For instance I have a string aaabbbccc i want the result to be abc. so far

Solution 1:

Fill a Set with the characters and concatenate its unique entries:

function makeUnique(str) {
  return String.prototype.concat(...new Set(str))
}

console.log(makeUnique('abc'));    // "abc"
console.log(makeUnique('abcabc')); // "abc"

Solution 2:

Convert it to an array first, then use the answer here, and rejoin, like so:

var nonUnique = "ababdefegg";
var unique = nonUnique.split('').filter(function(item, i, ar){ return ar.indexOf(item) === i; }).join('');

All in one line :-)

Solution 3:

Too late may be but still my version of answer to this post:

function extractUniqCharacters(str){
    var temp = {};
    for(var oindex=0;oindex<str.length;oindex++){
        temp[str.charAt(oindex)] = 0; //Assign any value
    }
    return Object.keys(temp).join("");
}

Solution 4:

You can use a regular expression with a custom replacement function:

function unique_char(string) {
    return string.replace(/(.)\1*/g, function(sequence, char) {
         if (sequence.length == 1) // if the letter doesn't repeat
             return ""; // its not shown
         if (sequence.length == 2) // if its repeated once
             return char; // its show only once (if aa shows a)
         if (sequence.length == 3) // if its repeated twice
             return sequence; // shows all(if aaa shows aaa)
         if (sequence.length == 4) // if its repeated 3 times
             return Array(7).join(char); // it shows 6( if aaaa shows aaaaaa)
         // else ???
         return sequence;
    });
}

Solution 5:

Using lodash:

_.uniq('aaabbbccc').join(''); // gives 'abc'