Callback in JS with API call

I'm new to APIs and I'm not able to implement a callback to add the elements of an array, ie make a post. I have a submit button that when clicked should read the array and add all the notes to the corresponding students. I have the array students and gradeValue. My addGradeToUsers function does POST, but I can not get it to run 3 times when I click on the submit button. How do I resolve this?

 function addGradeToUsers(student, gradeValue){
   showData();
   var orgUnitId= 167877;   //course number
   var gradeObjectId =111321; //grade name
    document.getElementById("PUTField").checked = true;
    document.getElementById("actionField").value = "/d2l/api/le/1.0/"+ orgUnitId +"/grades/"+ gradeObjectId+ "/values/"+ student +"";
    document.getElementById("dataField").value = "{\n \"Comments\":{\"Content\":\"null\",\"Type\":\"Text\"},\n \"PrivateComments\":{\"Content\":\"null\",\"Type\":\"Text\"},\n \"GradeObjectType\": 1,\n\"PointsNumerator\":"+gradeValue+" \n}";   
}


function addGrade(student, gradeValue, callback) 
{ 
   var students = [58686,58687, 392854];  // user Ids
   var gradeValues= [34,10,33];
    for(var i=0; i< students.length; i++){ 
        student=students[i];
        gradeValue=gradeValues[i];
        callback(student, gradeValue);
   }
}

Here my submit button:

<div class="form-group">
    <label for='contentType'>Importar Notas</label>
 <input class="btn btn-default" type="button" value="Add Grade to Users" onclick='addGrade(addGradeToUsers(58687,10))'>
  </div>