Question

Here are two samples of js code:

A. function _foo is defined within the global context

  function _foo(){ //some code here
  }

  //... some unrelated code here

  var foo = function(){
    var result = _foo();
    return result;
  }

B. function _foo is defined within the function context

var foo = function(){
  function _foo(){ //some code here 
  }

  var result = _foo();
  return result;
};

Which one of them is a better programming practice in terms of memory management? Since the function foo will be called many times in the application, is it better to keep _foo in the global context (of the app) and not create it within the function context everytime foo is called? Or since _foo will be (mostly) used inside foo, it makes sense to keep it part of the activation object?

Answer 1

C: Caching

var foo = (function(){
  function _foo(){ //some code here 
  }
  return function() {
    var result = _foo();
    return result;
  }
}());

Foo is immediately executed and the function _foo is only declared once.

In modern browsers this is 5% slower then a “global” function.

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