在Javascript上调用PHP函数Onchange

Question

I want to call a function in php onchange in select of html,how can this be done?

html code

<div class="col-sm-4 form-group">
   <label for="c_city">City</label>
   <select class="form-control" id="c_city" onchange="<?php getArea(); ?>">
        <option value="">Select City Name</option>
        <!--populate value using php-->
        <?php
            $stmt ="SELECT * FROM Cities";
            foreach ($con->query($stmt) as $row) {
         ?>
         <option value="<?php echo $row['City_ID'];?>"><?php echo $row['City_Name'];?></option>
         <?php
          }
         ?>
   </select>
</div>

PHP Functions Page

function getArea() 
{
    if(isset($_GET['c_city'])) 
    {
        $c_city = $_GET['c_city'];
        echo $c_city;
    }
}

Answer 1

You can try to use ajax to call the php script and receive results back to javascript.

For example in your html page:

<div class="col-sm-4 form-group">
   <label for="c_city">City</label>
   <select class="form-control" id="c_city" onchange="getArea()">
        <option value="">Select City Name</option>
        <!--populate value using php-->
        <?php
            $stmt ="SELECT * FROM Cities";
            foreach ($con->query($stmt) as $row) {
         ?>
         <option value="<?php echo $row['City_ID'];?>"><?php echo $row['City_Name'];?></option>
         <?php
          }
         ?>
   </select>
</div>

<script>
 function getArea(){
  var c_city = $('#c_city').val();
   $.ajax({
           type: 'POST',
           url: "get_area.php",
           data: {c_city:c_city},
           success: function(result){
               //do something here with return value like alert
               alert(result)
           }
     })
}
</script>

Then in your php script you can manipulate the value you receive from javascript

if(isset($_POST['c_city'])) 
    {
        $c_city = $_POST['c_city'];
        echo $c_city;
    }

Let me know if it helps or if you find a problem