Why are function declarations handled differently in different browsers?

Question

Although I couldn\'t find a reference to this easily in google, I\'m familiar with the fact that, in javascript, global function declarations get interpreted before any code

Answer 1

Function declarations are not valid in blocks. You have undefined behaviour which is undefined.

Function declarations at a top level (either global or top level within a function) are hoisted.

Function declarations inside blocks are a syntax error in strict mode

(function () { 
  "use strict"; 
  if (true) { 
    function g() { } 
  } 
})();

SyntaxError: In strict mode code, functions can only be declared at top level or immediately within another function.

Answer 2

The ECMA standard for this behavior is to throw a SyntaxError when parsing the script. Unfortunately doing that is not compatible with the web as Raynos says.

See Which JS function-declaration syntax is correct according to the standard? for some extended discussion on the issue.