Why is the variable inside this function global?

Question

I thought any variable defined in a function would be local but I can easily access variable 'e' outside of its function.

function change() {
 var d = 6; 
  e = 7;
}

change();
alert(e); //> alerts 7

Answer 1

Because new variables will enter the global scope by default. var prevents this from happening by constraining a variable's existence to be within the current scope.

Answer 2

Because it was declared without var it becomes part of the global window object.