Sample code to assume role and generate temporary credentials using .then()

AWS STS generate credentials using then().js

const AWS = require('aws-sdk');

const sts = new AWS.STS();
sts
  .assumeRole({
    DurationSeconds: 3600,
    ExternalId: '1234-1234-1234-1234-1234',
    RoleArn: 'Your Role ARN',
    RoleSessionName: 'abc',
  })
  .promise()
  .then(data => {
    console.log(data);
  })
  .catch(err => {
    console.log(err);
  });