I am a beginner using PnP js core Library. I am using PnP Js core library in my SharePoint web part to Display list Items from SharePoint list.

The code works fine in Chrome and Firefox browsers. When it Comes to IE 11 and Edge browsers -It says "Promise is undefined" i have used Es Promise and Ploy fill and fetch JS files.

Any Idea


3 Answers 3


PnPjs uses some browser APIs, which are not supported in IE\Edge. You should install polyfills in order to support them.

You should install them first:

npm install whatwg-fetch es6-promise --save

Then in your startup file (before any PnPjs use), add lines

import 'es6-promise/auto';
import 'whatwg-fetch';  

Basically, that's it.
Alternatively you can use polyfill service - read more here


For IE, you should load ES6-Promise and Fetch polyfills before PnP JS Core:

SharePoint/PnP-JS-Core not working for IE11


IE 11 Polyfill package Section on this pnp page will save your day https://pnp.github.io/pnpjs/documentation/polyfill/

This will surely help.

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