Showing unique characters in a string only once

Question

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.

Answer 1

<script>
    uniqueString = "";

    alert("Displays the number of a specific character in user entered string and then finds the number of unique characters:");

    function countChar(testString, lookFor) {
        var charCounter = 0;
        document.write("Looking at this string:<br>");

        for (pos = 0; pos < testString.length; pos++) {
            if (testString.charAt(pos) == lookFor) {
                charCounter += 1;
                document.write("<B>" + lookFor + "</B>");
            } else
                document.write(testString.charAt(pos));
        }
        document.write("<br><br>");
        return charCounter;
    }

    function findNumberOfUniqueChar(testString) {
        var numChar = 0,
            uniqueChar = 0;
        for (pos = 0; pos < testString.length; pos++) {
            var newLookFor = "";
            for (pos2 = 0; pos2 <= pos; pos2++) {
                if (testString.charAt(pos) == testString.charAt(pos2)) {
                    numChar += 1;
                }
            }
            if (numChar == 1) {
                uniqueChar += 1;
                uniqueString = uniqueString + " " + testString.charAt(pos)
            }
            numChar = 0;
        }
        return uniqueChar;
    }

    var testString = prompt("Give me a string of characters to check", "");
    var lookFor = "startvalue";
    while (lookFor.length > 1) {
        if (lookFor != "startvalue")
            alert("Please select only one character");
        lookFor = prompt(testString + "\n\nWhat should character should I look for?", "");
    }
    document.write("I found " + countChar(testString, lookFor) + " of the<b> " + lookFor + "</B> character");
    document.write("<br><br>I counted the following " + findNumberOfUniqueChar(testString) + " unique character(s):");
    document.write("<br>" + uniqueString)
</script>

Answer 2

Here is the simplest function to do that pt. 2

const showUniqChars = (text) => {
  let uniqChars = "";

  for (const char of text) {
    if (!uniqChars.includes(char))
      uniqChars += char;
  }
  return uniqChars;
};

Answer 3

Per the actual question: "if the letter doesn't repeat its not shown"

function unique_char(str)
{
    var obj = new Object();

    for (var i = 0; i < str.length; i++)
    {
        var chr = str[i];
        if (chr in obj)
        {
            obj[chr] += 1;
        }
        else
        {
            obj[chr] = 1;
        }
    }

    var multiples = [];
    for (key in obj)
    {
        // Remove this test if you just want unique chars
        // But still keep the multiples.push(key)
        if (obj[key] > 1)
        {
            multiples.push(key);
        }
    }

    return multiples.join("");
}

var str = "aaabbbccc";
document.write(unique_char(str));

Answer 4

Try this if duplicate characters have to be displayed once, i.e., for i/p: aaabbbccc o/p: abc

var str="aaabbbccc";
Array.prototype.map.call(str, 
  (obj,i)=>{
    if(str.indexOf(obj,i+1)==-1 ){
     return obj;
    }
  }
).join("");
//output: "abc"

And try this if only unique characters(String Bombarding Algo) have to be displayed, add another "and" condition to remove the characters which came more than once and display only unique characters, i.e., for i/p: aabbbkaha o/p: kh

var str="aabbbkaha";
Array.prototype.map.call(str, 
 (obj,i)=>{
   if(str.indexOf(obj,i+1)==-1 && str.lastIndexOf(obj,i-1)==-1){ // another and condition
     return obj;
   }
 }
).join("");
//output: "kh"

Answer 5

The one line solution will be to use Set. const chars = [...new Set(s.split(''))];

Answer 6

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;
    });
}