Problems clearing <textarea> after message is sent

Question

I'm currently making a web-based chat system but I've run into a problem. I have set up a function in javascript to check if the user presses enter in the textarea and send the message if this has happened. The problem is every time that function is used the textarea is left with a single carriage return in it as if the value of the textarea was "\\n" when it should be just "". Here's the code:

function checkEnter(e) {
 var charCode;
 if (e && e.which) {
  charCode = e.which;
 } else {
  charCode = e.keyCode;
 }
 if (charCode == 13) {
  say();
  document.getElementById('chatfieldbox').value = "";
  return false;
 } else {
  return true;
 }
}
function say() {
 updateStats();
 text = document.getElementById('chatfieldbox').value;
 xhr=new XMLHttpRequest();
 xhr.open("POST", "say", false);
 xhr.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
 xhr.setRequestHeader("Content-length", text.length);
 xhr.setRequestHeader("Connection", "close");
 xhr.send("text=" + text);
 document.getElementById('chatfieldbox').value = "";
 update();
}
function updateStats() {
 var text = document.getElementById('chatfieldbox').value;
 var num = text.length;
 var lines = 1;
 for (var i = 0; i < num; i++) {
  if (text.charAt(i) == '\n') {
   lines++;
  }
 }
 document.getElementById('characters').innerHTML = num;
 document.getElementById('lines').innerHTML = lines;
}

say(); does some ajax stuff to send the message. updateStats(); is just a character and line counter for the user's benefit. say(); sends the message to the server then calls to update to see if there are messages from anyone else to display (irrelevant). The HTML:

<textarea id="chatfieldbox" onKeyPress="checkEnter(event)"></textarea>

Any suggestions?

Answer 1

In your code the position of return false; makes sure that document.getElementById('chatfieldbox').value = ""; never gets called. Switch the positions of the two lines and it should work.

Answer 2

why don't you just clear out the textbox before you send the ajax request.

edit: also cancel event bubbling.

function say() {
    text = document.getElementById('chatfieldbox').value;
    document.getElementById('chatfieldbox').value = "";
    xhr=new XMLHttpRequest();
    xhr.open("POST", "say", false);
    xhr.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
    xhr.setRequestHeader("Content-length", text.length);
    xhr.setRequestHeader("Connection", "close");
    xhr.send("text=" + text);
    update();
}

function checkEnter(e) {
    var charCode;
    if (e && e.which) {
        charCode = e.which;
    } else {
        charCode = e.keyCode;
    }
    if (charCode == 13) {
        say();
        if (e.stopPropagation) {
            e.stopPropagation();
        } else {
            window.event.cancelBubble=true;
        }
        return false;
    } else {
        return true;
    }
}

Answer 3

A couple of things I guess would help:

Use the keyDown event(if not already):

textarea.onkeyDown = checkEnter;

In checkEnter you should pass the textarea reference to the say function:

if (charCode == 13) {
    elm = e.target || e.srcElement;
    say(elm);
    return false;
} else {
    return true;
}

And in the say function, clear the value when you get a positive response from the server.

function say(elm){
    var txt = elm.value;
    //make the ajax call and when done, call the 2nd param function
    call('say', function(resp){
        if(resp.ok){
            elm.value = '';
            doSomethingWith(txt);
        }else{
            //show error
        }
    });
}