国家乡村城市的Ajax

Question

Can anyone tell me why is it used and what will it produce in brief $(this).val(); also explain var dataString = 'state_id='+ id;

Here is the full code

$(document).ready(function(){     

  $(".state").change(function(){

    var id=$(this).val();
    var dataString = 'state_id='+ id;

    $.ajax({
      type: "POST",
      url: "city_names.php",
      data: dataString,
      cache: false,
      success: function(html)
      {           
        $(".city").html(html);
      } 

    });
  });

});

Thanks in advance.

Answer 1

This script will get list of all cities from state name/id:

$(document).ready(function()
{
  $(".state").change(function() // as state change, ajax will be called along with passing state value
  { 
    var id=$(this).val(); // it will contain the selected state value
    var dataString = 'state_id='+ id; // it will bind state value as post data to ajax
    $.ajax
    ({
      type: "POST",
      url: "city_names.php", // this file will find list of all city names from state name
      data: dataString, // it will pass parameters (state name)
      cache: false,
      success: function(html)
      {

        $(".city").html(html); // this will set list of cities in city list
      } 

    });
  });
});