Components of a binding handler

Binding handlers are defined by adding objects to the ko.bindingHandlers object, just like extenders. They are composed of an init and an update function.

The init function runs when the binding is first applied to the element either when ko.applyBindings is called or when the element is created by a control flow binding, such as template or foreach. It should be used for all one-time work such as attaching event handlers or disposal callbacks to the element.

The update function runs just after init does, when the binding is first applied. It runs again anytime when any observable dependencies are changed. The update function determines its dependencies just like a computed observable does. If an observable is accessed when an update runs, it subscribes to that observable. The update function should be used to keep the UI in sync with changes from the viewmodel:

ko.bindingHandlers.yourBindingName = {
    init: function(element, valueAccessor, allBindings, viewModel...

Tech Concepts

Programming languages

Tech Tools

Unlimited access to the largest independent learning library in tech of over 8,000 expert-authored tech books and videos.

Innovative learning tools, including AI book assistants, code context explainers, and text-to-speech.

50+ new titles added per month and exclusive early access to books as they are being written.

MASTERING KNOCKOUTJS

By : Timothy Moran

MASTERING KNOCKOUTJS

By: Timothy Moran

Overview of this book

Components of a binding handler

MASTERING KNOCKOUTJS

By : Timothy Moran

MASTERING KNOCKOUTJS

By: Timothy Moran

Overview of this book

Components of a binding handler

Confirmation

Buy this book with your credits?

Submit Your Feedback

Create a Free Account To Continue Reading

Sign in to activate your 7-day free access