using documentMode with typescript

Question

I check if the browser is ie by:

function isBrowserIE() {
  return window.document.documentMode;
}

Typescript raises an error:

Error TS2339: Property 'documentMode' does not exist on type 'Document'.

This is due to the change made in typescript compiler at version 1.5 :

Properties documentMode, parentWindow, createEventObject are removed from type Document

How can i get rid from the error?

Answer 1

I've used bracket notation to get rid of the error:
document['documentMode']

Answer 2

You can simply add it to the Document interface:

interface Document {
    documentMode?: any;
}

function isBrowserIE() {
    return window.document.documentMode;
}

---

Edit

If you are using modules then you need to use global augmentation:

declare global {
    interface Document {
        documentMode?: any;
    }
}