knockout.js

The pseudovariables are only available in the context of data binding. The view model itself ideally should not know about or have any dependencies on the view that is displaying it. So, when adding computed observables in the view model, you have no knowledge of how it will be bound (like what is going to … Read more

The reason is, that you’re indeed invoking the preview function (because writing functionName means referring to the function, writing functionName() means calling it). So data-bind=”click: Report.preview” would be working as expected, but without handing over the parameter. As the manual states (on a different topic, but this still applies): If you need to pass more … Read more

I needed this when selecting an <option> (that I was generating manually instead of built-in knockout). <option data-bind=”text: text, attr:{ value:value, ‘selected’: typeof(selected) !== ‘undefined’ ? selected : null }”> Choice X </option> This says to always update the ‘text’ attribute and to add the ‘value’ attribute, but only add ‘selected’ if the the data … Read more

Use extenders: ko.extenders.trackChange = function (target, track) { if (track) { target.isDirty = ko.observable(false); target.originalValue = target(); target.setOriginalValue = function(startingValue) { target.originalValue = startingValue; }; target.subscribe(function (newValue) { // use != not !== so numbers will equate naturally target.isDirty(newValue != target.originalValue); }); } return target; }; Then: self.MyProperty= ko.observable(“Property Value”).extend({ trackChange: true }); Now you … Read more