jquery - JavaScript alert function behaviour -

in asp.net, preventing default postback action when user presses enter while textbox control has focus. see following piece of code

      $("#textbox1").keydown(function(e)         {             if(e.keycode == 13)             {                 //alert("hello");                 return false;             }         }); 

this code works fine. if uncomment alert function call page post not stop.

my question why alert call creating problem?

i missed using keydown. prevent form submission, i'd use submit handler instead, in case working keydown handler , blur handler (to reset flag):

var cancelflag = false;  $('#textbox1')     .keydown(function(e) {         cancelflag = e.keycode == 13;     })     .blur(function() {         cancelflag = false;     });  $('#theform').submit(function() {     if (cancelflag) {         alert("hello!");     }     return cancelflag; }); 

(or can call e.preventdefault(); instead of returning false, either works.) you'll need testing ensure flag gets cleared in every situation want cleared in.

---

alternately, make alert asynchronous:

$("#textbox1").keydown(function(e) {     if(e.keycode == 13)     {         settimeout(function()         {             alert("hello");         }, 10);         return false;     } }); 

that lets event stack unwind before putting alert. i'm not @ sure can reliably (cross-browser , os) prevent form submission cancelling default action of keydown. said working, , if works in target browsers, great, but...