knockoutjs: can we create a dependentObservable function with a parameter?

Question

I have multiple input boxes that I want to hide/unhide based on a selection from user.

I can achieve this by having a separate dependentObservable for each input an

Answer 1

In Knockout, bindings are implemented internally using dependentObservables, so you can actually use a plain function in place of a dependentObservable in your bindings. The binding will run your function inside of a dependentObservable, so any observables that have their value accessed will create a dependency (your binding will fire again when it changes).

Here is a sample: http://jsfiddle.net/rniemeyer/2pB9Y/

html

type "one", "two", or "three":  

js

var viewModel = {
    text: ko.observable("one"),
    items: [{name: "one"}, {name: "two"}, {name: "three"}],
};

viewModel.shouldThisBeVisible = function(name) {
    return this.text() === name;
}.bind(viewModel);

ko.applyBindings(viewModel);