JavaScript_Succinctly

the bar variable. All this is to showcase the fact that functions can be passed around
just like any other value.
Invoking function statements before they are defined (aka function
hoisting)
A function statement can be invoked during execution before its actual definition. This is
a bit odd, but you should be aware of it so you can leverage it, or at least know what’s
going on when you encounter it. In the following sample, I invoke the sayYo() and
sum() function statements before they are defined.
Sample: sample96.html
// Example 1
var speak = function () {
sayYo(); // sayYo() has not been defined yet, but it can still be
invoked, logs 'yo'.
function sayYo() { console.log('Yo'); }
} (); // Invoke
// Example 2
console.log(sum(2, 2)); // Invoke sum(), which is not defined yet, but
can still be invoked.
function sum(x, y) { return x + y; }
This happens because before the code runs, function statements are interpreted and
added to the execution stack/context. Make sure you are aware of this as you use
function statements.
Notes
Functions defined as function expressions are not hoisted. Only function statements are
hoisted.
A function can call itself (aka recursion)
It’s perfectly legitimate for a function to call itself. In fact, this is often used in well-known
coding patterns. In the code that follows, we kick off the countDownFrom function, which
then calls itself via the function name countDownFrom. Essentially, this creates a loop
that counts down from 5 to 0.
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