I need help to get data from xml file using javascript

Hi everyone.
I'm begginer in Javascript language and i need help.I'm trying to get data from web page thats actually xml file using javascript.I'm learining this and i already did example when you download xml file and have file on computer and than to extract data and i complete this, but now i need someone to help me and show me on example how to get data from xml file which is on web page and show results in new window,
Hope somebody will help me with this and help me in my learning Javascript.

Thanks everybody in advance.