Heroku has official document to teach how to get Laravel work on Heroku platform. But if you has Bower / Gulp for your Laravel project, you need to set the app to run with php buildpack, you also need to run this to get your app run as NodeJs app:
$ heroku buildpacks:add –index 1 heroku/nodejs
Once you have this setting effect for your app, you can utilize package.json to have this to run the bower and gulp:
“scripts”: {
“postinstall”: “bower install && gulp”
}