string="hi you. im dr.test. nice to see you. by the way, what was your name?";

    string=string.split("");

     up=false;

    for(key in string){

      if(string[key]=="."){

        up=true;

      }

      if(up&&string[key]!==" "){

        string[key]=string[key].toUpperCase();

        up=false;

       }}

      string=string.join("");

 console.log('result:',string);