Hoisting JS elevator code

Here is the best answer: Mozilla Quote off the site: "Using var outside a function is optional; assigning a value to an undeclared variable implicitly declares it as a global variable (it is now a property of the global object). The difference is that a declared variable is a non-configurable property of the global object while an undeclared is configurable."

The 'var' key is important for a few reasons: 1) it allows not only yourself but others to understand your code and the defined variables within it; 2) as Mozilla (via Paul) states, it allows you to understand Global vs. Local var declarations. If you declare a var outside a function, it is accessible anywhere because it is a global var; whereas if you defined a var within a function it is only accessible within that function (local). By not using the var keyword to define a var, you could accidentally modify a global var or create and define a new global var without realizing it, thus making the debugging process that much more complex.