removing validation error

removing validation error

I have a question related to jquery. Basically I want to do a very simple thing. I have a text input field. On submit, I want to display error message if the field is empty.
I have done this way:

  1. errMsg = "Please write name";              
  2. $("div#errMsg").css("background-color", "red");
  3.  $("div#errMsg").html(errMsg);

and in the HTML:
  1. <div id="errMsg"></div>
  2. <strong>Name:  </strong>
  3. <input name="name" id="name" type="text" maxlength="255" size="50" />

It works fine, however there is a problem. When I leave the field empty and it displays the error message, the error message does not go away without refreshing the page.
I am trying to do it so that when there is error message, and i type something in the field, it automatically remove the error without refreshing the page.
Any help would be much appreciated. Thanks.