stringsToNumber-high

/* Write a function addThreeNumsFromString that takes a single string
 * as argument. The given string will consist of three numbers
 * separated by a space. The function will add the three the numbers
 * and return their sum.
 */

/* This is the high-level view of what's going wrong with this
 * program.
 */

console.log(addThreeNumsFromString("5 5 5"))
// will log 15
console.log(addThreeNumsFromString("4 2 1"))
// will log 7


//Your Answer:
var sum = 0;

// For my explanations of this function, just assume that the argument
// is the string "5 5 5".
function addThreeNumsFromString (str){
  /* What did you want to do here?
   * - What you wanted to do:
   *   Split the string into just the numbers, and ignore everything
   *   else. Correct statement is:
   *      var newArr = str.split(" ")
   * - What you did:
   *   Split the string into individual characters:
   */
  var newArr = str.split("");
   */
  /* What did you want to do in this loop?
   * - You wanted to loop through the numbers in the string.
   *   for (var i = 0; i < newArr.length; i++) {
   * - What you actually did: loop through the *whole string* (all the
   *   characters in the string).
   */
   for (var i = 0; i < str.length; i++) {
    /* - What you wanted to say here:
     *   Take the ith number in the string and add that to sum.
     *   Correct statement:
     *     sum += Number(newArr[i])
     * - What you actually did: take the ith *string* in newArr and
     *   add that to sum.
     * - What you actually wanted to do is further complicated by
     *   trouble with scope here. Where does `sum` actually live? It's
     *   not defined in `addThreeNumsFromString`, it's defined in the
     *   enclosing scope, when you said `var sum = 0`. Handuful of
     *   wrong details here, but I'll cover those in a more detailed
     *   breakdown, later.
     */
    sum += newArr[i]
  }
  /* Returning your sum is the right thing to do, but is also
   * complicated by troubles with scope. You can see this by running
   * this function more than once and observing the return value.
   */
  return sum;
}