const options = {method: 'POST', headers: {Authorization: 'Basic <encoded-value>'}};
fetch('https://virtserver.swaggerhub.com/BangoProducts/Reseller-API/1.0.23/v1/echo/{echoRequestId}', options)
.then(res => res.json())
.then(res => console.log(res))
.catch(err => console.error(err));