function btnclick() {
  var v = document.getElementById('msg').value.replace('\x0d','');
  document.getElementById('demoimg').setAttribute('src', '/cgi-bin/msgimgdemo.pl?'+encodeURI(v));
}
document.getElementById('demo').innerHTML =
'<div class="section">'+
'<h2>Demonstration</h2>'+
'<form action=""><fieldset>'+
'<label for="msg">Enter test message:</label>'+
'<textarea id="msg" name="msg" rows="5" style="vertical-align:top">Hello, world!</textarea>'+
'<button type="button" onclick="btnclick()">Make image</button>'+
'</fieldset></form>'+
'<p><img id="demoimg" src="" alt="" /></p>'+
'</div>'+
'<hr class="sectiondiv" />';
btnclick();