knockout.js event that tracks every text change inside a input text box

Question

I'm new to knockout js. I want to call a function every time a text changes inside a text box. I researched a bit and implemented keyup, keydown and keypress but they didn't work properly. If anybody could give me a solution or please redirect me to some document that is helpful for my scenario. And If there is some sort of documentation about all of the events (inbuilt and custom) that are available in knockout Js, that would be really helpful.

To be specific about the problem:

  data-bind="value: targetProp, event:{keyup: $parent.changeProp}"

And in Js:

    Inside parent:
     this.changeProp = function () {
                if (condition..) {
                       do something...
                }
            }
      

It's not working with key up. For simple solution, please give me something that will alert the length of the string that has been written inside a textbox (on every text entered and deleted).

Answer 1

You can use valueUpdate: 'afterkeydown' which updates your view model as soon as the user begins typing a character.

data-bind="value: targetProp, valueUpdate: 'afterkeydown'"