In most cases, the value of a function's this
argument is determined by how the function is called. This lesson explains what this
refers to when we call plain function. Marius points out how functions behave differently in strict and non-strict mode. "use strict"
mode defaults this
to undefined and prevents us from assigning values to undefined. We must call functions as a constructor to assign their this
value correctly.
there's a typo in the transcript: "It doesn't matter whether are not the cause side is in strict mode. "
should be "It doesn't matter whether or not the call site is in strict mode."
http://prntscr.com/izvmmd even i am not in the use strict mode, it is not assigning firstName and last Name to the global scope. Just adding this new keyword before Person object prevented defining variables to the global scope.