Get value from text field and post it in a javascript variable

[tonyaligenclik]

I have this script:\[code\]<script>var dataoriginale = document.getElementById("savedataoriginale").value;</script>\[/code\]and this text field:\[code\]<input name="savedataoriginale" id="savedataoriginale" type="text" value="http://stackoverflow.com/questions/14562964/testtest">\[/code\]but when I try to print the javascript var\[code\]<script>document.write(dataoriginale)</script>\[/code\]I get undefined.Why? How can I fix that?