Questions on a couple parts of the code

<script>
var message = '';
var student;
var search; // why do we put some variables up here but not others? (such as report)
// This (search) variable is declared in global scope. Therefore accessible from anywhere in your code.


function print(message) {
  var outputDiv = document.getElementById('output');
  outputDiv.innerHTML = message;
}
// (report) Since declared within that function is only accessible from that function and any nested functions. 
function getStudentReport( student ) {
// this (report) variable is declared in local scope. only accessed in this function. 
  var report = '<h2>Student: ' + student.name + '</h2>';
  report += '<p>Track: ' + student.track + '</p>';
  report += '<p>Points: ' + student.points + '</p>';
  report += '<p>Achievements: ' + student.achievements + '</p>';
  return report;
}

while (true) {
  search = prompt("Please enter a student name: "); // why do we not use var here like we did in getStudentReport?
// We are starting a while loop here, so we can loop threw the prompt method. until it is we say quit.
  if (search === null || search.toLowerCase() === 'quit') { // when we say quit
    break;// stop the loop if the previous statement is true.
  } // why do we not use else here? can else be implied if left blank in JavaScript?
// we want to loop threw all the students entered in the search variable. and print the information we entered in the prompt.
    for (var i = 0; i < students.length; i += 1) {
      student = students[i]; 
      if ( student.name === search ) {
        message = getStudentReport ( student );
        print(message);
      }
    }
}
</script>