Categories: javascript, php, html, ajax

Js, PHP WITH AJAX: how to determine the letter grade of students using javascript with ajax?

1 answer

So I made a program about an exam and I need to determine the letter grades of students but first, they have to answers some questions then base on what score the student gets the student will get a letter grade, someone recommended me to use AJAX because I need to do the process itself in the form without refreshing so I tried to make it but I ended up getting confused can someone help me, please.

Iā€™m confused because everytime I got the score the letter grades are not appearing

Here are the codes:

        <div class = "form">     <button id = "submit" name = "submit"  value = "submit" > SUBMIT </button>     <div id="myModal" class="modal">       <div class="modal-content">         <h3> Are you sure you want to submit? </h3>         <button id = "yes" name = "yes" class = "yes" value = "submit" onclick ="loadDoc()"> YES </button>         <button id = "no" name = "no" class = "no"> NO </button>       </div>     </div>       <div id="myModalLast" class="modalLast">       <div class="modal-contentLast">        <a href = "personal.php"> <span class="close">&times;</span> </a>      <div class = "pic">         <img src="Logo.png" width = "150" height = "150">     </div>           <h3> Full name: Cathleen Joyce Imperial Almeda </h3>           <h3> Total items:20 <p id = "score" name = "scorename"></p> </h3>          <h1> <br><p id = "scores" name = "realscores"></p>         Rank:<p id = "rank"></p>     </h1>         </div>     </div>     </div> 

This is for the ajax part:

        <script>     function loadDoc() {       var xhttp = new XMLHttpRequest();       xhttp.onreadystatechange = function() {         if (this.readyState == 4 && this.status == 200) {           document.getElementById("score").innerHTML =           this.responseText;         }       };"post", "examExtension.php", true);       xhttp.send();     }     </script> 

And this for examExtension.php:

        <?php       $score = isset($_POST['score']) ? $_POST['score'] : '';       if ($score > 19 and $score < 21){     echo "A+";     }     if($score  > 18 and $score< 20){     echo "A";     }     if($score  > 17 and $score< 19){     echo "A-";     }     if($score  > 16 and $score< 18){     echo "B+";     }     if($score  > 15 and $score < 17){     echo "B";     }     if($score  > 14 and $score< 16){     echo "B-";     }     if($score  > 13 and $score< 15){     echo "C+";     }     if($score  > 12 and $score < 14){     echo "C";     }     if($score  > 11 and $score< 13){     echo "C-";     }     if($score  > 10 and $score< 12){     echo "D+";     }     if($score  > 9 and $score< 11){     echo "D";     }      ?> 

And lastly, this is for the counting of scores it is based on how many radio buttons the student correctly clicked.

         <script>document.getElementById("yes").addEventListener("click", function() {       let numberOfCorrectAnswers = document.querySelectorAll("input[type=radio].correct:checked").length;       document.getElementById("score").innerHTML = "Your Score: " + numberOfCorrectAnswers;       });       </script> 

Thanks in advance for the help!

All answers to this question, which has the identifier 61230967

The best answer:

You are getting a blank value because you are not sending anything to your PHP script. Your examExtension.php script expects a value called score. Without that value all the if statements are coming up false and thus nothing is ever returned to your request.

You can pass a value into the xhttp.send() function to send the score to your PHP file so it can read it and calculate a result for you.

const scoreElement = document.getElementById("score"); const yesButton = document.getElementById("yes");  yesButton.addEventListener("click", function() {   let numberOfCorrectAnswers = document.querySelectorAll("input[type=radio].correct:checked").length;    // Pass amount of correct answers to the loadDoc function.   loadDoc(numberOfCorrectAnswers);   console.log('Calculating grade'); });  // Use the 'numberOfCorrectAnswers' value as the 'score' variable in this function. function loadDoc(score) {   var xhttp = new XMLHttpRequest();   xhttp.onreadystatechange = function() {     if (this.readyState == 4 && this.status == 200) {       scoreElement.innerHTML = "Your Score: " + this.responseText;       console.log('Grade calculation complete');     }   };"post", "examExtension.php", true);    // Send the score like this.   // This will look like 'score=18' and can be read by your PHP file.   xhttp.send('score=' + score); } 
<?php  // Check if the score is given. If it is, continue. Otherwise stop the script. if (!isset($_POST['score']) {   echo 'No score has been given';   exit; }  // Convert score value to a number. $score = intval($_POST['score']);  if ($score > 19 and $score < 21) {   echo "A+"; } else if ($score > 18 and $score < 20) {   echo "A"; } else if($score > 17 and $score < 19) {   echo "A-"; } else if ($score > 16 and $score < 18) {   echo "B+"; } else if ($score > 15 and $score < 17) {   echo "B"; } else if ($score > 14 and $score < 16) {   echo "B-"; } else if ($score > 13 and $score < 15) {   echo "C+"; } else if ($score > 12 and $score < 14) {   echo "C"; } else if ($score > 11 and $score < 13) {   echo "C-"; } else if ($score > 10 and $score < 12) {   echo "D+"; } else if($score  > 9 and $score < 11) {   echo "D"; }  exit;  ?> 

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