utils.ts

import * as keys from './keys';

export function bindArguments(args) {
  for (var i = args.length - 1; i >= 0; i--) {
    if (typeof args[i] === 'function') {
      args[i] = global.zone.bind(args[i]);
    }
  }
  return args;
};

export function patchPrototype(obj, fnNames) {
  fnNames.forEach(function (name) {
    var delegate = obj[name];
    if (delegate) {
      obj[name] = function () {
        return delegate.apply(this, bindArguments(arguments));
      };
    }
  });
};

export function isWebWorker() {
  return (typeof document === "undefined");
}

export function patchProperty(obj, prop) {
  var desc = Object.getOwnPropertyDescriptor(obj, prop) || {
    enumerable: true,
    configurable: true
  };

  // A property descriptor cannot have getter/setter and be writable
  // deleting the writable and value properties avoids this error:
  //
  // TypeError: property descriptors must not specify a value or be writable when a
  // getter or setter has been specified
  delete desc.writable;
  delete desc.value;

  // substr(2) cuz 'onclick' -> 'click', etc
  var eventName = prop.substr(2);
  var _prop = '_' + prop;

  desc.set = function (fn) {
    if (this[_prop]) {
      this.removeEventListener(eventName, this[_prop]);
    }

    if (typeof fn === 'function') {
      
      function wrapFn(event) {
        var result;
        result = fn.apply(this, arguments);
        
        if (result != undefined && !result)  
          event.preventDefault();
      };

      this[_prop] = wrapFn;
      this.addEventListener(eventName, wrapFn, false);
    } else {
      this[_prop] = null;
    }
  };

  desc.get = function () {
    return this[_prop];
  };

  Object.defineProperty(obj, prop, desc);
};

export function patchProperties(obj, properties?) {
  (properties || (function () {
      var props = [];
      for (var prop in obj) {
        props.push(prop);
      }
      return props;
    }()).
    filter(function (propertyName) {
      return propertyName.substr(0,2) === 'on';
    })).
    forEach(function (eventName) {
      patchProperty(obj, eventName);
    });
};

var originalFnKey = keys.create('originalFn');
var boundFnsKey = keys.create('boundFns');

export function patchEventTargetMethods(obj) {
  // This is required for the addEventListener hook on the root zone.
  obj[keys.common.addEventListener] = obj.addEventListener;
  obj.addEventListener = function (eventName, handler, useCapturing) {
    //Ignore special listeners of IE11 & Edge dev tools, see https://github.com/angular/zone.js/issues/150
    if (handler && handler.toString() !== "[object FunctionWrapper]") {
      var eventType = eventName + (useCapturing ? '$capturing' : '$bubbling');
      var fn;
      if (handler.handleEvent) {
        // Have to pass in 'handler' reference as an argument here, otherwise it gets clobbered in
        // IE9 by the arguments[1] assignment at end of this function.
        fn = (function(handler) {
          return function() {
            handler.handleEvent.apply(handler, arguments);
          };
        })(handler);
      } else {
        fn = handler;
      }

      handler[originalFnKey] = fn;
      handler[boundFnsKey] = handler[boundFnsKey] || {};
      handler[boundFnsKey][eventType] = handler[boundFnsKey][eventType] || global.zone.bind(fn);
      arguments[1] = handler[boundFnsKey][eventType];
    }

    // - Inside a Web Worker, `this` is undefined, the context is `global` (= `self`)
    // - When `addEventListener` is called on the global context in strict mode, `this` is undefined
    // see https://github.com/angular/zone.js/issues/190
    var target = this || global;
    return global.zone.addEventListener.apply(target, arguments);
  };

  // This is required for the removeEventListener hook on the root zone.
  obj[keys.common.removeEventListener] = obj.removeEventListener;
  obj.removeEventListener = function (eventName, handler, useCapturing) {
    var eventType = eventName + (useCapturing ? '$capturing' : '$bubbling');
    if (handler && handler[boundFnsKey] && handler[boundFnsKey][eventType]) {
      var _bound = handler[boundFnsKey];
      arguments[1] = _bound[eventType];
      delete _bound[eventType];
      global.zone.dequeueTask(handler[originalFnKey]);
    }

    // - Inside a Web Worker, `this` is undefined, the context is `global`
    // - When `addEventListener` is called on the global context in strict mode, `this` is undefined
    // see https://github.com/angular/zone.js/issues/190
    var target = this || global;
    var result = global.zone.removeEventListener.apply(target, arguments);
    return result;
  };
};

var originalInstanceKey = keys.create('originalInstance');

// wrap some native API on `window`
export function patchClass(className) {
  var OriginalClass = global[className];
  if (!OriginalClass) return;

  global[className] = function () {
    var a = bindArguments(arguments);
    switch (a.length) {
      case 0: this[originalInstanceKey] = new OriginalClass(); break;
      case 1: this[originalInstanceKey] = new OriginalClass(a[0]); break;
      case 2: this[originalInstanceKey] = new OriginalClass(a[0], a[1]); break;
      case 3: this[originalInstanceKey] = new OriginalClass(a[0], a[1], a[2]); break;
      case 4: this[originalInstanceKey] = new OriginalClass(a[0], a[1], a[2], a[3]); break;
      default: throw new Error('what are you even doing?');
    }
  };

  var instance = new OriginalClass();

  var prop;
  for (prop in instance) {
    (function (prop) {
      if (typeof instance[prop] === 'function') {
        global[className].prototype[prop] = function () {
          return this[originalInstanceKey][prop].apply(this[originalInstanceKey], arguments);
        };
      } else {
        Object.defineProperty(global[className].prototype, prop, {
          set: function (fn) {
            if (typeof fn === 'function') {
              this[originalInstanceKey][prop] = global.zone.bind(fn);
            } else {
              this[originalInstanceKey][prop] = fn;
            }
          },
          get: function () {
            return this[originalInstanceKey][prop];
          }
        });
      }
    }(prop));
  }

  for (prop in OriginalClass) {
    if (prop !== 'prototype' && OriginalClass.hasOwnProperty(prop)) {
      global[className][prop] = OriginalClass[prop];
    }
  }
};