public/assets/knockout-3-4-0/src/binding/defaultBindings/event.js

   1 // For certain common events (currently just 'click'), allow a simplified data-binding syntax
   2 // e.g. click:handler instead of the usual full-length event:{click:handler}
   3 function makeEventHandlerShortcut(eventName) {
   4     ko.bindingHandlers[eventName] = {
   5         'init': function(element, valueAccessor, allBindings, viewModel, bindingContext) {
   6             var newValueAccessor = function () {
   7                 var result = {};
   8                 result[eventName] = valueAccessor();
   9                 return result;
  10             };
  11             return ko.bindingHandlers['event']['init'].call(this, element, newValueAccessor, allBindings, viewModel, bindingContext);
  12         }
  13     }
  14 }
  15
  16 ko.bindingHandlers['event'] = {
  17     'init' : function (element, valueAccessor, allBindings, viewModel, bindingContext) {
  18         var eventsToHandle = valueAccessor() || {};
  19         ko.utils.objectForEach(eventsToHandle, function(eventName) {
  20             if (typeof eventName == "string") {
  21                 ko.utils.registerEventHandler(element, eventName, function (event) {
  22                     var handlerReturnValue;
  23                     var handlerFunction = valueAccessor()[eventName];
  24                     if (!handlerFunction)
  25                         return;
  26
  27                     try {
  28                         // Take all the event args, and prefix with the viewmodel
  29                         var argsForHandler = ko.utils.makeArray(arguments);
  30                         viewModel = bindingContext['$data'];
  31                         argsForHandler.unshift(viewModel);
  32                         handlerReturnValue = handlerFunction.apply(viewModel, argsForHandler);
  33                     } finally {
  34                         if (handlerReturnValue !== true) { // Normally we want to prevent default action. Developer can override this be explicitly returning true.
  35                             if (event.preventDefault)
  36                                 event.preventDefault();
  37                             else
  38                                 event.returnValue = false;
  39                         }
  40                     }
  41
  42                     var bubble = allBindings.get(eventName + 'Bubble') !== false;
  43                     if (!bubble) {
  44                         event.cancelBubble = true;
  45                         if (event.stopPropagation)
  46                             event.stopPropagation();
  47                     }
  48                 });
  49             }
  50         });
  51     }
  52 };