Meteor client side asynchronous callback

How to get value return by the asynchronous call back in the client side of meteor before stack continue to execute? something like :

var result=function(str){
      Meteor.call("getSearch",str,function(err,res){
    if (err)
      throw new Error(err.message);
    else 
      return res
      });
    };

    var final=result(text);
    console.log(final);

How can I get the value of final before it print out? Thanks.