WordPress won’t save javascript code

For those places where the user can enter content, the Save process checks the capability of the user before saving. If the user does not have unfiltered_html capability, then the javascript is stripped out.
But your description sounds a little different, as if the Save process is hanging. When you say “in plugins when I click save it gives a problem”, is there an error? You probably should ask at that plugin’s support forum.
If the widget is a core widget, which one is it and what is the error? (otherwise ask at the plugin’s forum that supplies the widget)