public/assets/knockout-2-2-1/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, allBindingsAccessor, viewModel) {
   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, allBindingsAccessor, viewModel);
  12         }
  13     }
  14 }
  15
  16 ko.bindingHandlers['event'] = {
  17     'init' : function (element, valueAccessor, allBindingsAccessor, viewModel) {
  18         var eventsToHandle = valueAccessor() || {};
  19         for(var eventNameOutsideClosure in eventsToHandle) {
  20             (function() {
  21                 var eventName = eventNameOutsideClosure; // Separate variable to be captured by event handler closure
  22                 if (typeof eventName == "string") {
  23                     ko.utils.registerEventHandler(element, eventName, function (event) {
  24                         var handlerReturnValue;
  25                         var handlerFunction = valueAccessor()[eventName];
  26                         if (!handlerFunction)
  27                             return;
  28                         var allBindings = allBindingsAccessor();
  29
  30                         try {
  31                             // Take all the event args, and prefix with the viewmodel
  32                             var argsForHandler = ko.utils.makeArray(arguments);
  33                             argsForHandler.unshift(viewModel);
  34                             handlerReturnValue = handlerFunction.apply(viewModel, argsForHandler);
  35                         } finally {
  36                             if (handlerReturnValue !== true) { // Normally we want to prevent default action. Developer can override this be explicitly returning true.
  37                                 if (event.preventDefault)
  38                                     event.preventDefault();
  39                                 else
  40                                     event.returnValue = false;
  41                             }
  42                         }
  43
  44                         var bubble = allBindings[eventName + 'Bubble'] !== false;
  45                         if (!bubble) {
  46                             event.cancelBubble = true;
  47                             if (event.stopPropagation)
  48                                 event.stopPropagation();
  49                         }
  50                     });
  51                 }
  52             })();
  53         }
  54     }
  55 };