JSFiddle - React, Tailwind, and code Playground

by ronilan

HTML

<pre>
  // How do you detect for the first repeated character in a string? 
</pre>

JavaScript

// How do you detect for the first repeated character in a string? 

function firstRepeatedChar (str) {
	
  var result = null;
  var found = false;
  var max = str.length;
  var i,
  		j;
  
  for (i = 0; i < max;  i++) {
    for (j = 0; j < i;  j++) {
      if (str.substr(i, 1) === str.substr(j, 1)) {
      	found = true;
        result = str.substr(i, 1);
        break;
      }
    }
    if (found) {
    	break;
    }
	}
	return result;
}


/** Tests
* A set of test cases for sumTwoLargest.
* Note, you may use factory functions to generate test cases.
**/

var tests = [{
  case: 'abc',
  expected: null
}, {
  case: 'abcdec',
  expected: 'c'
}, {
  case: 'aAbBcCdDeeFf',
  expected: 'e'
}, {
  case: (function () {
    'use strict';
    return [1, 1, 5].join();
  }()),
  expected: '1'
}];

/**
* Test Runner
* Runs the above tests and prints true/false to console.
**/

(function () {

  'use strict';

  /**
  * assertEqual will return true if both inputs are equal and false if not;
  *
  * @param {string} a - first
  * @param {string} b - second
  * @return {boolean} - are eqaul?
  **/
  function assertEqual (a, b) {

    return a === b;
  }

  var i = tests.length;
  while (i) {
    i--;
    window.console.log(assertEqual(firstRepeatedChar(tests[i].case), tests[i].expected));
  }
}());