Undefined jscript in javascript

You are probably getting this error due to a missing semicolon. Change the code to this:

var myvariableName = {};

You're probably accessing the variable before your external script is executed.

Be sure to access your variable as soon as the document is fully loaded (i.e. $(document).ready(function(){...}); if you use jQuery) or try to find out the real execution order with some alert (that shouldn't be browser-depentent, by the way!).

In your asp page, where you access your custom variable, wrap your code with:

var myvariableName = {};

window.onload = function(){

  // your code here where you're accessing the variable

};

If your code is already in a document.load or $(document).ready(function) you can always handle the variable before acessing it via

if (typeof myvariableName !== "undefined") {
    // do stuff
}

Some times in IE shit happens and window.load gets screwed specially when async calls are in place.

Try wrapping your code inside an IIFE (Immediately Invoked Function Expression). After you set the variable make it a property of the window so that it is global in scope.

(function() {   
    var common = 'this is a global variable.';
    window.common = common;  
}) ();