Using keypress event in knockout JS

• Check that the query is an observable
• Use   valueUpdate = ‘afterkeydown’
• Use   event: { ‘keyup’: check }:

   Use the  console.log if possible as opposed to alert, and log the query to check the  value is updating.. For log the event ,See this

function check(data, event)
{
  console.log(event);
}

   The KO docs, at least as of now, specifically addresses this issue:

Note 1: textInput vs value binding

   Eventhough the value binding do two-way binding between text boxes and viewmodel properties, Then prefer the textInput whenever sudden live updates is needed.

See   http://knockoutjs.com/documentation/textinput-binding.html