How can I process each letter of text using Javascript?

If the order of alerts matters, use this:

for (var i = 0; i < str.length; i++) {
  alert(str.charAt(i));
}

Or this: (see also this answer)

 for (var i = 0; i < str.length; i++) {
   alert(str[i]);
 }

If the order of alerts doesn’t matter, use this:

var i = str.length;
while (i--) {
  alert(str.charAt(i));
}

Or this: (see also this answer)

 var i = str.length;
while (i--) {
  alert(str[i]);
}

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