A handy little tip, if all you need to do is rip out spaces in a string don't bother with using slice(), use regex instead. Copy the following line of code and replace '-' with whatever you need to replace the space with...
yourString = yourString.replace(/s+/g, '-');
So for example, if yourString="blah blah blah", it will now become "blah-blah-blah". This is especially useful for amending URLs.
Happy new year!