Generate instant previews for image upload

Hey all, I was recently working with the image upload and the problem I came across was to show the previews of the image being/to-be uploaded. After few trial-and-error attempts, I found pretty neat solution with FileReader api.

Code:

Following is the vanilla js solution for that:

And can be used in following ways:

If you are fan of Promises, you can define and use the above code in folowing ways:

Playground:

The following playground uses above callback based code. No data is sent to server.

Image: