Tracking array adds and removes is not quite as simple as it first appears...

addremoveexample.js

// Initialise array with some data and track changes
var trackedArray = ko.observableArray([1,2,3]).extend({trackArrayChanges: true});

trackedArray.getChanges();
// -> { } No changes yet

trackedArray.push(4);
trackedArray.pop();

trackedArray.getChanges();
// -> { } Changes have negated each other