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From: James Kirk <noneya.invalid@gmail.com>
Newsgroups: comp.lang.javascript
Subject: Re: custom event in IE
Date: Wed, 11 Jan 2017 21:31:45 -0500
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Thomas 'PointedEars' Lahn <PointedEars@web.de> wrote:

> James Kirk wrote:

>> Andrew Poulos <ap_prog@hotmail.com> wrote:=20

>>> I used a try/catch and when it fails for IE the "catch" part uses
>>> initCustomEvent

[snip]

>> I have always tried to avoid using try/catch. So just out of my own
>> curiosity, why the try/catch over something liking to the function

[snip]

> If the global object has no CustomEvent property in the MSHTML DOM,
> then such a polyfill would be a possibility. If on the other hand it
> has such a property but the value of it just cannot be called a
> constructor, then the value would be a reference to a host object,
> and it would be unwise to try to overwrite the value.

I would not agree with =E2=80=9Cunwise=E2=80=9D, ill-advised perhaps, I sup=
pose it
really depends on what definition was intended. No argument intended.

I did not intend to infer the usage of the Polyfill example verbatim.

Perhaps something similar to the following:

(function () {

  var CustomEvent =3D function (event, params) {
    console.log('petaQ');
    params =3D params || {
      bubbles: false,
      cancelable: false,
      detail: undefined
    };
    var evt =3D document.createEvent('CustomEvent');
    evt.initCustomEvent(event,=20
	                params.bubbles,=20
			params.cancelable,=20
			params.detail);
    return evt;
  }
  if (typeof (window.CustomEvent) =3D=3D=3D "function") {
    CustomEvent =3D window.CustomEvent;
  }
/*=20

more script follows

*/

})();

>> or testing in a similar fashion to that function.=20

> You cannot determine whether a function can be called as a
> constructor unless you try it.

No know evidence to refute that.

In IE 11 typeof window.CustomEvent =3D=3D=3D 'object'. I am going to surmise
the same for IE 9 & 10.

[url]http://caniuse.com/#feat=3Dcustomevent[/url]

Presuming that support for anything older then IE 11 is not being
handled. Is there a reason to redetermine if CustomEvent can be called
as a constructor?

As I previously stated, =E2=80=9Ccuriosity, why the try/catch=E2=80=9D, in =
no way do I
oppose the use of try/catch.


--=20
James Kirk