Knockout validation: Сomparison of the two fields

February 04, 2013

I would like to share how I've solved this problem.

The typical example is a simple registration form with the view model:

var viewModel = ko.validatedObservable({
    userName: ko.observable().extend({ required: true }),
    password: ko.observable().extend({ required: true }),
    passwordConfirm: ko.observable().extend({ required: true })

Then you can easily check is your viewModel valid using:


And it works very good. But you don't have validation are your password and password confirmation fields equal.

To do it you have to add these lines:

viewModel().password.extend({ equal: viewModel().passwordConfirm });
viewModel().passwordConfirm.extend({ equal: viewModel().password });

After that you will have client notification as well as ability to check is your view model valid in code (as mentioned above).

That's all.
Good luck.

Recommended content


Leave your comment