upsert.js

'use strict';

var key = 'YOURAPIKEY'
  , SparkPost = require('sparkpost')
  , client = new SparkPost(key)
  , listEntry = {
    recipient: 'test1@test.com',
    transactional: false,
    non_transactional: true,
    description: 'Test description 1'
  };

// Promise
client.suppressionList.upsert(listEntry)
  .then(data => {
    console.log('Congrats you can use our client library!');
    console.log(data);
  })
  .catch(err => {
    console.log('Whoops! Something went wrong');
    console.log(err);
  });

// Callback
client.suppressionList.upsert(listEntry, function(err, data) {
  if (err) {
    console.log('Whoops! Something went wrong');
    console.log(err);
  } else {
    console.log('Congrats you can use our client library!');
    console.log(data);
  }
});