Challenge: In your own words

gistfile1.txt

Q: Why are global variables avoided?
A: Because their values can be overwritten by the values of local variables.
   Local scope (function scope) can have access to global scope.
   Sometimes this can be useful like when we want global access to a library
   like JQuery in all our files. Or we want a function to have access in a database.

Q: Explain JavaScript's strict mode
A: When 'strict mode' is enabled declaring a variable without the var keyword, will rise an error.
  The 'use strict' command can be put at the top of a file to enforce strict mode for the entire file.

Q: What are side effects, and what is a pure function?
A: Global variables tend to make side effects in a program. A side effect is when a function reaches
   outside its local scope, up into a parent scope (bacause of scope chaining) and alters its value.
   A pure function is a function where the return value is only determined by its input values,
   without side effects.

Q: Explain variable hoisting in JavaScript
A: Hoisting is the JavaScript interpreter’s action of moving all variable
   and function declarations to the top of the current scope.
   However, only the actual declarations are hoisted. Asignments are left where they are.