Have a look at Knockout-Validation which cleanly setups and uses what’s described in the knockout documentation. Under: Live Example 1: Forcing input to be numeric You can see it live in Fiddle UPDATE: the fiddle has been updated to use the latest KO 2.0.3 and ko.validation 1.0.2 using the cloudfare CDN urls To setup ko.validation: … Read more
I know this is an old thread, but I was having the same problem and found out a much better solution that was probably added to knockout after this question was officially answered, so I’ll just leave it for people with the same problem. Currently there is no need for extenders, custom binding handlers or … Read more
You should use ko.utils.unwrapObservable in cases where you don’t know if you have been given an observable or not. This would commonly be in a custom binding where an observable or non-observable could be bound against it. In the code that you have above, the call to valueAccessor() is not actually unwrapping an observable. It … Read more
The bootstrap buttons and the knockout checked binding are still not playing nice: knockout uses the click event inside the checked binding to tigger the underlaying observable to change bootstrap subscribes on the click event to do the toggling but calls e.preventDefault() so KO won’t be notified about the click. One possible solution is to … Read more
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 … Read more
It sounds like you were on the right track. You basically want to do the equivalent of: click: function() { return true; }, clickBubble: false OR This could be done in a custom binding like: ko.bindingHandlers.stopBubble = { init: function(element) { ko.utils.registerEventHandler(element, “click”, function(event) { event.cancelBubble = true; if (event.stopPropagation) { event.stopPropagation(); } }); } … Read more
I’m sure there are a variety of ways to do this. I manually render the view from the controller, and then pass the rendered view back as part of my JSON response. This preserves the responsibilities of each entity. Views are still located using the view engine and they can be reused. The controller knows … Read more
Is better to create custom binding http://knockoutjs.com/documentation/custom-bindings.html which accept only allowed characters [0-9,.] as numeric representation. put this line into your view <input id=”text” type=”text” data-bind=”numeric, value: number”> put this line into your model (remember to bind number as observable property) ko.bindingHandlers.numeric = { init: function (element, valueAccessor) { $(element).on(“keydown”, function (event) { // Allow: … Read more
You have the afterRender callback in knockout.js: foreach: { data: myItems, afterRender: renderedHandler } Here’s documentation. Inside your handler check whether the length of the rendered collection is equal to the length of the items collection. If not don’t execute the full rendered logic that you intend to use. renderedHandler: function (elements, data) { if … Read more
An alternative that does not rely on the order that the fields are bound is to have the binding set an id property on the data itself, which would need to be an observable. ko.bindingHandlers.uniqueId = { init: function(element, valueAccessor) { var value = valueAccessor(); value.id = value.id || ko.bindingHandlers.uniqueId.prefix + (++ko.bindingHandlers.uniqueId.counter); element.id = value.id; … Read more