Right & Wrong: Loop recursion

loop_recursion_right.js

function Students(classroom){
  this.relationships = {};
  this.reverseSearchMap = {};
  this.students = classroom.students;
}

Students.prototype.populate = function(){
  for(var index = 0; index < this.students.length; index++){
    var student = students[index];
    var studentName = this.fullNameForStudent(student);
    relationships[studentName] = [];
    this.addOthersToStudentWithName(studentName);
  }
};

Students.prototype.fullNameForStudent = function(student){
  return student.firstName.concat(' ', student.lastName);
};

Students.prototype.addOthersToStudentWithName = function(studentName){
  for(var index = 0; index < this.students.length; index++){
    var otherStudentName = this.fullNameForStudent(this.students[index]);
    if(otherStudentName.is(studentName))
      relationships[studentName].push(otherStudentName);
    
    var name = Array.prototype.slice.call(otherStudentName);
    addNameToInitials(studentName, name);
  }
};

Students.prototype.addNameToInitials = function(studentName, name){
  for(var index = 0; index < name.length; index++){
    var otherStudentInitial = name[index];
    this.reverseSearchMap[otherStudentInitial] = this.reverseSearchMap[otherStudentInitial] || [];
    this.reverseSearchMap[otherStudentInitial].push(studentName);
  }
}

var students = new Students({
  title: 'Foo Classroom', 
  students: ['Ryan', 'Shane', 'Ana', 'Junnan', 'Hayley']
});
students.populate();

loop_recursion_wrong.js

/* Wrong */
function uniqueRelationshipsFromClassroom(classroom) {
  var relationships = {};
  var reverseSearchMap = {};
  var students = classroom.students;
  
  for(var i = 0; i < students.length; i++){
    var student = students[i];
    var studentName = student.firstName.concat(' ', student.lastName);
    relationships[studentName] = [];
    
    for(var j = 0; j < students.length; j++){
      var otherStudent = students[j];
      var otherStudentName = otherStudent.firstName.concat(' ', otherStudent.lastName);
      var shouldAdd = otherStudentName.is(studentName);
      shouldAdd && (relationships[studentName].push(otherStudentName));
      
      var name = Array.prototype.slice.call(otherStudentName);
      for(var k = 0; k < name.length; k++){
        var otherStudentInitial = name[k];
        reverseSearchMap[otherStudentInitial] = otherStudentInitial || [];
        reverseSearchMap[otherStudentInitial].push(studentName);
      }
    }
  }
}

var classroom = {
  title: 'Foo Classroom', 
  students: ['Ryan', 'Shane', 'Ana', 'Junnan', 'Hayley']
};
uniqueRelationshipsFromClassroom(classroom);

One is longer, but it's much easier to determine what level you're at, and isolate your analyzation to a specific area of code.