OTPAuth

import * as OTPAuth from 'otpauth';

// Create a new TOTP object.
let totp = new OTPAuth.TOTP({
    issuer: 'ACME',
    label: 'AzureDiamond',
    algorithm: 'SHA1',
    digits: 6,
    period: 30,
    secret: 'NB2W45DFOIZA' // or "OTPAuth.Secret.fromB32('NB2W45DFOIZA')"
});

// Generate a token.
let token = totp.generate();

// Validate a token.
let delta = totp.validate({
    token: token,
    window: 1
});

// Convert to Google Authenticator key URI.
//   otpauth://totp/ACME:AzureDiamond?issuer=ACME&secret=NB2W45DFOIZA&algorithm=SHA1&digits=6&period=30
let uri = totp.toString(); // or "OTPAuth.URI.stringify(totp)"

// Convert from Google Authenticator key URI.
let parsedTotp = OTPAuth.URI.parse(uri);

// @deno-types="https://deno.land/x/otpauth/types/index.d.ts"
import * as OTPAuth from 'https://deno.land/x/otpauth/dist/otpauth.esm.js'

// Same as above...

<script src="otpauth.umd.js"></script>
<script>
    // Same as above...
</script>