Question

Hi i know valueUpdate: afterkeydown will do model update after user input but I want to know how can i do valueUpdate automatically after some other javascript code changes value

I have a js code that does document.getElementById(“input”).value = “new value”;

do i have to update model manually or what valueUpdate should i use.

Answer 1

If you trigger the change event for the element, then the element’s binding (value) will pick up the change and process it normally.

However, generally you would want to make your updates through the view model and let the bindings handle setting the element’s properties, but if you have 3rd party or existing code that interacts directly with the element that cannot be changed, then triggering the change event is a solution.

Knockout does include a utility to trigger an event properly cross-browser called ko.utils.triggerEvent.

Your code might look like:

   var elem = document.getElementById("input");
   elem.value = "new value";
   ko.utils.triggerEvent(elem, "change");