How To/Convert title string to url slug

When making your urls looking better, you may want to convert a title to a url-slug.

An url-slug is in common a string containing only alphanumeric letters and ‘-’. Following lua function converts a normal title string to a url-slug.

function toSlug(str)
	return string.gsub(string.gsub(str,"[^ A-Za-z]",""),"[ ]+","-")
end

The toSlug function also replaces multiple spaces with one ‘-‘ only.