Js gets the implementation code for the value and text of the drop down box selected item

Js to get the value of the drop-down box and the text on the web provides two ways: but some people are very irresponsible, they do not take into account the differences between the browser caused by the error, resulting in many novice pondering for a long time to find the error!

Below I summarize the following to get the value and text of the selected item in the drop-down box under Firefox and IE:

Js implementation of the current page opens a new link:
Window. The location. Href = url;