I had an image file on my filesystem and I wanted to put it inside an HTML page using the data-uri format so I could embed it into the page itself.

Here’s how I did it:

const imageData = fs.readFileSync(fileLocation, 'binary')

const src = `data:${contentType};base64,${Buffer.from(
  imageData,
  'binary'
).toString('base64')}`

In my case I just download that image from the Internet, so I retrieved contentType from the response headers:

const contentType = response.headers['content-type']

In the end I was able to use src inside an img tag like this: <img src={src} />