coderbyte "Simple Symbols"

app.js

/* Have the function SimpleSymbols(str) take the str parameter being passed 
   and determine if it is an acceptable sequence by either returning true or false.
   The str parameter will be composed of + and = symbols with several letters between them (ie. ++d+===+c++==a)
   and for the string to be true each letter must be surrounded by a + symbol.
*/

function SimpleSymbols(str) {
  var result;
  var letterCounter = 0;
  var successCounter = 0;
  var letters = ["a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"];
  var chars = str.split('');
  
  for (var k in chars) {
    if (letters.indexOf(chars[k]) !== -1) {
      letterCounter += 1;
      if (chars[k - 1] === '+' && chars[k + 1] === '+') successCounter += 1;
    }
  }
  
  if (letterCounter === successCounter) { return console.log(true); }
  else { console.log(false); }
}

SimpleSymbols('+d+=3=+s+');