deploy.js

const zipFolder = require('zip-folder');
var fs = require('fs');

let folder = 'build';
let zipName = 'build.zip';

// getting all the credentials and IDs from `gitlab-ci.yml` file
let REFRESH_TOKEN = process.env.REFRESH_TOKEN;
let EXTENSION_ID = process.env.EXTENSION_ID;
let CLIENT_SECRET = process.env.SECRET;
let CLIENT_ID = process.env.CLIENT_ID;

const webStore = require('chrome-webstore-upload')({
    extensionId: EXTENSION_ID,
    clientId: CLIENT_ID,
    clientSecret: CLIENT_SECRET,
    refreshToken: REFRESH_TOKEN
});

// zipping the output folder
zipFolder(folder, zipName, function (err) {
    if (err) {
        console.log('oh no!', err);
        process.exit(1);
    } else {
        console.log(`Successfully Zipped ${folder} and saved as ${zipName}`);
        uploadZip(); // on successful zipping, call upload 
    }
});

function uploadZip() {
    // creating file stream to upload
    const extensionSource = fs.createReadStream(`./${zipName}`);

    // upload the zip to webstore
    webStore.uploadExisting(extensionSource).then(res => {
        console.log('Successfully uploaded the ZIP');

        // publish the uploaded zip
        webStore.publish().then(res => {
            console.log('Successfully published the newer version');
        }).catch((error) => {
            console.log(`Error while publishing uploaded extension: ${error}`);
            process.exit(1);
        });

    }).catch((error) => {
        console.log(`Error while uploading ZIP: ${error}`);
        process.exit(1);
    });
}