Knockout : How to check whether bindings have been applied to page area

Question

Is there a way to check whether applyBindings has been called for a page area or not?

It seems knockout doesn't like when applyBindings is called on the same page more than once.

Answer 1

Knockout 2.0 has two functions that you could use for this purpose. ko.dataFor and ko.contextFor take in a node and return either the Knockout data that would be available to it for binding at that scope (dataFor) or the entire binding context at that scope (contextFor), which includes $data, $parent, $parents, and $root.

So, you can do something like:

var isBound = function(id) {   return !!ko.dataFor(document.getElementById(id)); }; 

Here is a sample: http://jsfiddle.net/rniemeyer/GaqGY/

However, in a normal scenario you should really look to call ko.applyBindings a single time on your page. It depends on what you are trying to accomplish though. Take a look at this answer for some suggestions on ways to manage multiple view models: Example of knockoutjs pattern for multi-view applications.

Typically, you would do a <div data-bind="with: mySubModel"> and when mySubModel gets populated then that area would appear and be bound.