如何使用JavaScript变量作为键访问PHP数组元素？

Question

So I am trying to make a simple academic system. I made dynamic boxes which show course information. Core code looks like this

function addcourses(){  //(numcourses)
    var num_courses= <?php echo $_GET['num']?>; //=numcourses
    var newdiv;
    var divIdName;
    var i=0;
    for(i=1;i<=num_courses;i++){
        var divtoadd = document.getElementById('courselist');
        newarticle = document.createElement('article');
        divIdName = 'course'+i;
        newarticle.setAttribute('id',divIdName);
        newarticle.innerHTML ='<div class="box"><h2><?php echo $course_num_arr[i]?></h2><div class="content"><p>Credit Hours: <?php echo $credit_arr[0]?> </p><p>Professor: <?php echo $prof_arr[0]?></p><p>Average GPA: <?php echo $avg_arr[0]?></p><p>GPA: <?php echo $gpa_arr[0]?></p></div></div>';
        call_course();        
        divtoadd.appendChild(newarticle);
    }
}

The problem is with <?php echo $course_num_arr[i]?> since i is the variable from javascript, I don't know how to deal with this.

I want to echo $course_num_arr[1] when i = 1 and $course_num_arr[2] when i = 2 and so on.

Answer 1

If you don't want to use ajax call and wants to place the code in the PHP file, your can use json_encode() function. Please refer below code.

<?php
$cources = array( "0" => array ("name" => "maths","credits" => 30),"1"
=> array ("name" => "physics","credits" => 30));
?>
<script>
data=<?php echo json_encode($cources); ?>;
for(i=0;i<data.length;i++){
    alert(data[i].name)
    var h = document.createElement("H1");
    var t = document.createTextNode(data[i].name);
    h.appendChild(t);
    document.body.appendChild(h);
}
</script>