Design issue: client side or server side?
I am a django/python developer and my logic is "templates should be used for rendering". I keep my load minimum on the client side and all computation is done on the server side.
Another reason for doing this is because a user cannot be trusted. Keep the equation simple for the user.
Whenever there is dilemma to do a particular task, which can be accomplished either by client side code or by using a server code, which should be preferred?
For example:
I can iterate through a javascript object and construct a string and then send it to server, or should i send the javascript object and process it in the server?
My views: whenever I come across this situation I use the client side code as it reduces the computation load on server. 
What has to be done in such a situation? Which is the right approach?