JS function statement vs function expression

gistfile1.txt

function expression
function
optional name
parameters
  wrapped in ()
  zero or more names
  separated by a comma
body
  wrapped in {}
  zero or more statements
  
Produces an instance of a functon object
Function objects are first class
  may be passed as an argument to a function
  may be returned from a function
  may be assigned to a variable
  may be stored in an object or array
Function objects inherit from Function.prototype, so functions can have methods
A variable declared anywhere within a function is visible everywhere within the function.


function statement - same as function expression except the name is mandatory
function
mandatory name
parameters
  wrapped in ()
  zero or more names
  separated by commas
body
  wrapped in {}
  zero or more statements
  
The function statement is a short-hand for a var statement with a function value:
  function foo () {}
expands to
  var foo = function foo () {};
which further expands to
  var foo = undefined;
  foo = function foo () {};
The assignment of the function is also hoisted.  So function statements should be declared at the top level of its parent function if in a function.

In the standards function statements are called function declarations.