"'Promise' is undefined" in IE11

I’m testing the pnp.js of the latest PnP-JS-Core, using an Install and Use example

The example includes the use of promise. The instructions say that this will fail in IE11 unless I add the es6-promise polyfill and the fetch polyfill and include them in the example.

So I did, but in IE11, when invoking the invocation of “then”:

$pnp.sp.web.select("Title").get()
.then(function (data) {
    document.getElementById("main").innerText = 'Web title: ' + data.Title;
})
.catch(function (ex) {
    document.getElementById("main").innerText = 'Exception: ' + ex;
});

still fails with the exception: “‘Promise’ is undefined”.

Any suggestions why that might be?

[ray007]

Seems I maybe do not have the latest version here, “catch” needs to be a quoted property: Promise.prototype['catch'] = ...

[daryllabar]

I’m getting an error in IE 11: Expected identifier (1075,21) IE 11 has a bug in it’s JS engine (at least on my machine it does) where catch is not interpreted as a function name, but as a try{}catch(){} and is failing…

	Promise.prototype.catch = function _catch(onRejection) {
		return this.then(null, onRejection);
	};

If I fix that error, I also get the same error on the finally.

Maybe this is due to compatibility mode? Am I doing something wrong?

Looks like this was an IE Compatibility issue. The minified or the es6-promises actually does have the [“catch”] and [“finally”] values defined correctly.