I am attempting to fix and issue with my code. I was originally using DOMNodeRemoved and DOMNodeInserted for keeping an eye on an element within a page I am working on. They worked well but did not function in IE. So I started trying to work with a MutationObserver.

Here is my Code it's called on onPageInit(the callback writes to the console but I disabled it since IE no longer supports console):

var callback = function(allmutations){

    allmutations.map( function(mr){

        var mt = 'Mutation type: ' + mr.type;  // log the type of mutation

        mt += 'Mutation target: ' + mr.target; // log the node affected.

        //console.log( mt );

    })

}

mo = new MutationObserver(callback),

options = {

    // required, and observes additions or deletion of child nodes.

    'childList': true, 

    // observes the addition or deletion of grandchild nodes.

    'subtree': true

}

alert('its alive');

mo.observe(document.body, options);

It works fine in chrome, however for some reason falls flat in IE. I get a message box during load of the page that says :

An unexpected error occurred in a script running on this page.

onPageInit(pageInit)

scriptname



JS_EXCEPTION

TypeError 'MutationObserver' is undefined

Am I doing something wrong?
Additional info:
Page is a netsuite page, running jQuery 1.7.2 (if it matters)