Blog / Random thoughts and musings.

Javascript namespacing

I’ve been writing a lot more Javascript recently, and have occasionally run into variable and function naming conflicts, where I pick a name, not realizing that some other Javascript library that I’m using already has a function or variable with that name. This leads to a lot of troublesome, unnecessary debugging.

For a while, I used the old-fashioned technique of prefacing all my variable and function names with something fairly unique, like my initials. So instead of a variable named “i” I would have “mdf_i”. Messy, and ugly, and more than half the time I would forget to do it.

Doing a Google search for “javascript namespace” brought back quite a few results of the type:

1. Something needs to be done
2. Javascript doesn’t have any built-in support for this
3. Here’s what I do

After looking through the suggestions, I’ve started using Dustin Diaz’s solution. Here’s a quick example script I put together that shows how it works, using a new object “mdf” that contains all my code:

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var mdf = function() {
 
  // This can be accessed only from methods inside mdf
  var vtest1 = 'vtest1';
 
  // This can be accessed only from methods inside mdf
  function ftest1() {
    alert('inside ftest1');
  }
 
  // Public methods are part of the returned object:
 
  return {
 
    // mdf.ftest2() can be accessed from the main javascript
    // scope or from another mdf method
    ftest2 : function() {
      alert('inside ftest2');
    },
 
    // To execute a public method of mdf, specify the mdf object
    ftest3 : function() {
      mdf.ftest2();
    },
 
    // To access a private function or variable, use it normally
    ftest4 : function() {
      ftest1();
      alert(vtest1);
    }
  };
}();
 
alert(vtest1);   // This will fail
ftest1();        // This will fail
mdf.ftest4();    // This will succeed