Run script if selected value is changed

Question

I want to run a PHP script if the value is changed in my dropdown . The PHP script should run an if else statement. Is it possible to run this script, without a form POST?

Here is my dropdown:

<select id="data" name="data" class="select2_single form-control">
  <option value="1">Data 1</option>
  <option value="2">Data 2</option>
</select>

Here is the script I want to execute:

<?php
  if($_POST['data'] != '1') {
    echo  'Value 1 is selected';
  }
  if($_POST['data'] != '2') {
    echo 'Value 1 is selected';
  } else {
    echo  'No value selected';
  }
?>

Answer 1

Try this js code for change value and handle post data at php end:

$(document).ready(function() {
  $("#data").change(function() {
    var id=$(this).val();       
    $.ajax
    ({
        type: "POST",
        data: 'id='+ id, 
        url : "dynamic_select.php",
        success: function(data) {
            //Handle returned data 
        }
    });

   });

});

Answer 2

Also you can do this using just plain JavaScript:

 var dataEl = document.querySelector('#data'), outputEl = document.querySelector('#output'); dataEl.onchange = function() { outputEl.innerText = dataEl.value ? 'Value ' + dataEl.value + ' is selected' : 'No value selected'; }; 

 <select id="data" name="data" class="select2_single form-control"> <option value="">Select...</option> <option value="1">Data 1</option> <option value="2">Data 2</option> </select> <p id="output"></p>