sales-data.js

var WPAPI = require( 'wpapi' );
var RSVP = require('rsvp');

// Using the RSVP.hash utility for convenience and parallelism
RSVP.hash({
  categories: wp.categories().slug( 'it-services' ),
  tags1: wp.tags().slug('hotel-name'),
  tags2: wp.tags().slug('march-events')
}).then(function( results ) {
    // Combine & map .slug() results into arrays of IDs by taxonomy
    var tagIDs = results.tags1.concat( results.tags2 )
        .map(function( tag ) { return tag.id; });
    var categoryIDs = results.categories
        .map(function( cat ) { return cat.id; });
    return wp.posts()
        .tags( tags )
        .categories( categories );
}).then(function( posts ) {
    // These posts are all fiction, either magical realism or historical:
    console.log( posts );
});