How to match the word in jquery

I have the image and i am fade in and fade out the image on click. But i want that if the same is present then it should not fadein/fadeout.

My jquery code is

 switch(current_id)
                {

                    case 'l1':
                        $("#left_img img").fadeOut(500, function() {
                        $(this).attr("src","rrr.gif").load( function() {
                        $(t开发者_如何学Chis).fadeIn(500);
                                });
                                });
                    break;

                    case 'l3':
                        $("#left_img img").fadeOut(500, function() {
                        $(this).attr("src","cc1.gif").load( function() {
                        $(this).fadeIn(500);
                                });
                                });
                break;  

If i click on link 1 then image A appears with fade effect. but if i click again link 1 agan , then again i see fade effect . Is there any way i can avoid that if same link is clicked again

---

try adding another variable to check...

var last_id;

if (last_id != current_id) {
last_id = current_id;
    switch(current_id){
    case 'l1':
       $("#left_img img").fadeOut(500, function() {
       $(this).attr("src","rrr.gif").load( function() {
       $(this).fadeIn(500);
            });
            });
   break;
   case 'l3':
      $("#left_img img").fadeOut(500, function() {
      $(this).attr("src","cc1.gif").load( function() {
      $(this).fadeIn(500);
            });
            });
   break;  
   }
}

---

Do a check on the src attribute of the image - if it wasn't already change do the effect and load it in.

switch(current_id)
         {

             case 'l1':
               if($(left_img img").attr("src") != "rrr.gif") {
                    $("#left_img img").fadeOut(500, function() {
                    $(this).attr("src","rrr.gif").load( function() {
                    $(this).fadeIn(500);
                            });
                            });
                }
                break;

              case 'l3':
                if($("#left_img img").attr('src') != "cc1.gif") {
                    $("#left_img img").fadeOut(500, function() {
                    $(this).attr("src","cc1.gif").load( function() {
                    $(this).fadeIn(500);
                            });
                            });
                }
            break;