This code will create a contact off the back of a form submission whereby a user is prompted to provide details for a plus 1.

plus1referral.js

const hubspot = require('@hubspot/api-client');

exports.main = async (event, callback) => {

    const fname = event.inputFields['firstname'];
    const lname = event.inputFields['lastname'];
    const plus1FirstName = event.inputFields['plus_1_first_name'];
    const plus1LastName = event.inputFields['plus_1_last_name'];
    const plus1EmailAddress = event.inputFields['plus_1_email_address'];

    const hubspotClient = new hubspot.Client({
        apiKey: process.env.HAPIKEY
    });

    const properties = {
        "email": plus1EmailAddress,
        "firstname": plus1FirstName,
        "lastname": plus1LastName,
        "plus_1_for": fname + " " + lname
    };

    const SimplePublicObjectInput = {
        properties
    };

    try {
        const ApiResponse = await hubspotClient.crm.contacts.basicApi.create(SimplePublicObjectInput);
        callback({
            outputFields: {
                "plus1": plus1FirstName + " " + plus1LastName
            }
        });
    } catch (err) {
        console.error(err);
        throw err;
    }
}