Pressing the first button...
results in a different page being loaded in the same window.
how to retrieve the query string ('par=59')...
and how to determine its URL.
The second button,...
results in another document being shown in another window. Could be a new window, could be an existing one or a frame, depending on whether 'windowname' already exists.
The third argument to 'window.open' is a string with options.
/xxx/ and /yyy/ are regular expressions, that's why they're not in quotes. The effect is, that the window's size will be one quarter of the screen resolution.
Refreshing a page can be done in this manner. 'true', because we want a genuine reload, a reload from the server, not from the browser cache.
Clicking the 4th button...
show a couple interesting 'navigator' members in the textarea.
At times one wishes to avoid cluttering the history. At such a time one can resort to using