JavaScript Variable returning null when entering for loop

Question

I'm working on some code that should output the accumulation of a string eg.

abc would = A Bb Ccc

But when I test it the input and output get assigned abc and "" respectively, but once the for loop happens the code just stops and returns null.

Anyone can explain why? I tried SubString instead of charAt to no avail.

function accum(s) {

  //storage
  var input = s;
  var output = "";

  // capitalize first letter
  for (var i = 0; i < s; i++) {
    output = input.charAt(i);
    output.toUpper();

    for (var j = i; j < i; j++) {
      output += output.toLower();
    };

    return output;
  };

}
console.log(accum("abc"));

Did you mean i < s.length? Did you mean .toUpperCase() and .toLowerCase()? — nnnnnn
– nnnnnn, Commented Oct 10, 2016 at 6:28
yes.. awesome thanks. Getting my head around switching syntax, the tool I'm using didn't even bring these up as errors — theHussle
– theHussle, Commented Oct 10, 2016 at 6:30
might as well be!, no I run it through pythontutor.com/javascript.html#mode=edit, which is really good. But doesn't advise of any syntax errors etc — theHussle
– theHussle, Commented Oct 10, 2016 at 8:29

cs01 · Accepted Answer · 2016-10-10 06:31:03Z

1

I believe the first for loop should have the condition i < s.length, as opposed to i < s.

answered Oct 10, 2016 at 6:31

cs01

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