Question

I often see this in code: var me = this;. Why is that? Is there some performance gain if I reference ‘this’ in local variable?

Answer 1

It’s useful if there are functions inside a function, such that code in those nested functions needs access to the value of this from the outer context.

function example() {
  var me = this;
  document.getElementById('whatever').onclick = function() {
    me.clicked = 1;
  };
}

Because this is established anew for every function call, without stashing the outer this in a variable there’d be no way to reference it at all from the inner function.