[cs] Extend JQuery to bind changes in content, and skip general keypresses.

onValChange.js.coffee

# Bind changes in content. Skip general keypresses.
$.fn.onValChange = (callback) ->

  # IE < 9
  usePropertyChange = true
  this.on("propertychange.onValChange", (e) =>
    callback.call(this) if (e.originalEvent.propertyName == "value")
    return
  )

  # HTML5
  this.on("input.onValChange", (e) =>
    # This event fires before the above, unbinding it if we're not in IE.
    if usePropertyChange
      this.off("propertychange.onValChange")
    callback.call(this)
    return
  )