javascript - Textarea count characters validation -

i'm writing asp page using vb.net , need count number of characters in textarea , display message:"x characters remaining."

that's asp code:

  <td valign='top'>                 <textarea rows="5" id="content_txt" name="textarea1" runat="server" maxlength="50"></textarea>             </td> 

here jsfiddle

html:

<textarea rows="5" id="content_txt" name="textarea1" runat="server" maxlength="50"></textarea> <p id="message"></p> 

js:

var area = document.getelementbyid("content_txt"); var message = document.getelementbyid("message"); var maxlength = 50; var checklength = function() {     if(area.value.length < maxlength) {         message.innerhtml = (maxlength-area.value.length) + " characters remaining";     } } setinterval(checklength, 300);