I'm working on a worldwide website (all in one single domain) so I'm wondering to create dynamic titles, descriptions, keywords and headings for each location.

What I'm doing is to get information from the IP of the user and show for example a dynamic title:

var userCity = codeToGetCityFromIP;

<title>Welcome to userCity</title>
// and same for description, keywords and headings...

Obviously the code is different...

I'd like to know if it is a good solution to create multiple SEO indexing based on cities?

I'm also using GeoLocation and I do same using the returned values from it.

I'm doing right or there are more effective ways to indexing in different countries and cities without create multiple website for each city of the world?

Thanks.