Assignment of anonymous function to onkeyup handler

for CSCI E3, Harvard University author(s): Larry Bouthillier

by DustyWhite

HTML

Type a brief bio here:<br>
<textarea id="bio" cols="60" rows="6"></textarea>

<p>You typed:</p>
<div id="echoLocation" style="width:60em;height:6em;"></div>

JavaScript

// first we'll get the HTMLElement objects for the 
// textarea and the div where we want to write the
// output

var textareaElement = document.getElementById("bio");
var echo = document.getElementById("echoLocation");

// now we'll assign a function to the 'onkeyup' handler for the
// textarea element. This function gets run every time the user
// completes a keystroke in the textarea.
textareaElement.onkeyup = function(){
    echo.innerHTML = textareaElement.value;
}