function toggle() {
	var pattern1e=/eng/g
	var pattern1f=/fra/g
	var here=location.href

	if (pattern1e.test(here)) {
		here=here.replace(pattern1e, "fra")
		}
	else 
	{	if (pattern1f.test(here)) 
			here=here.replace(pattern1f, "eng")
		}
	location.href=here
	}