Question

I want to make a check box checked automatically (using jquery) when a user select an option from a certain select input element .

Coding :

$("#cboUser").change(function(){

    $.ajax({
                       type: "POST",
                       url: "sysnuser",
                       data: "slcbo=slcbo&uid="+ $("#cboUser").val() ,
                       success: function(html){
                           $("#divmsg").html(''); 
        }
    }); 
});

<select class="textboxforall" id="cboUser" name="cboUser" >
   <option value="1">1</option>
   <option value="2">2</option>
</select>   

<input type="checkbox" id="check1" name="check1" ?> 

Answer 1

If you mean you want checkbox to be checked on changing select, then:

$(document).ready(function() {
$("#cboUser").change(function(){
  var optId = $(this).val();
   //check the checkbox
   $("#check"+optId).attr("checked", "checked");
    $.ajax({
           type: "POST",
           url: "sysnuser",
           data: "slcbo=slcbo&uid="+ $("#cboUser").val() ,
           success: function(html){
           $("#divmsg").html(''); 
        }
    }); 
});
});

Hope it helps