Pushing updates from event log to webpage not working in IE8

问题

In my MVC4 application I have some code to push a new entry in the eventlog to a webpage with SignalR. This code works in FireFox, but in IE8 when a new event is added to the event log the debugger pops up with Error: Object doesn't support this property or method and stops at the following code:

this.notifyListeners = function (queryName, evt) {
        registeredListeners.forEach(function (item) {
            if (item.queryName === queryName) {
                item.listener.newEvent(evt);
            }
        });
    };

When I step over this method the debugger closes and the event is shown on the page. Why does this happen and how can I workaround this?

回答1:

forEach is not supported in IE8 you need to polyfill

Like suggested here:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/forEach

if (!Array.prototype.forEach)
{
  Array.prototype.forEach = function(fun /*, thisArg */)
  {
    "use strict";

    if (this === void 0 || this === null)
      throw new TypeError();

    var t = Object(this);
    var len = t.length >>> 0;
    if (typeof fun !== "function")
      throw new TypeError();

    var thisArg = arguments.length >= 2 ? arguments[1] : void 0;
    for (var i = 0; i < len; i++)
    {
      if (i in t)
        fun.call(thisArg, t[i], i, t);
    }
  };
}

Or perform and standard for loop, something like:

this.notifyListeners = function (queryName, evt) {
  var item={};
  for (i=0;i<registeredListeners.length;i++){
    item = registeredListeners[i];
            if (item.queryName === queryName) {
                item.listener.newEvent(evt);
            }
  }
};

来源：https://stackoverflow.com/questions/21312537/pushing-updates-from-event-log-to-webpage-not-working-in-ie8