title: Is there a use for NOT using var, let or const?
body: <p>I looked at tons of questions/answers on the "no var" topic but I'm still confused</p>
  
  <blockquote>
    <p>"no var" will look up the scope chain until it finds the variable or
    hits the global scope (at which point it will create it)</p>
  </blockquote>
  
  <p>I get this, but what does "no var" do if it does find something? e.g if you want to change an existing variable or binding, do you use var/let again or is it OK if you don't? Is there a difference?</p>