Knockout Computed Observable

by Joshua McKearin

HTML

<script src="http://ajax.aspnetcdn.com/ajax/knockout/knockout-2.2.1.js"></script>
Name:
<input data-bind="value: name, valueUpdate: 'afterkeydown'" />
<input type="checkbox" data-bind="checked: nameVisible" />
<p>
    Hello, <span data-bind="text: name, visible: nameVisible"></span>
    <br /> 
    <span data-bind="text: displayName"></span>
</p>
<button data-bind="click: changeName">Change Name</button>

JavaScript

$(function () {
    var viewModel = {
        name: ko.observable("Bob"),
        changeName: function () {
            this.name("Steve");
        },
        nameVisible: ko.observable(true)
    };

    viewModel.displayName = ko.computed(function () {
        return this.name() + " is" + (!this.nameVisible() ? " not" : "") + " visible";
    }, viewModel);

    ko.applyBindings(viewModel);
});