Usando o Fontawesome 5 no Laravel 5.5 via NPM

font-awesome.js

/**
 * Font Awesome 5 - Set of icons and most popular web tools.
 */
import fontawesome from '@fortawesome/fontawesome';
import solid from '@fortawesome/fontawesome-free-solid';
import regular from '@fortawesome/fontawesome-free-regular';
import brands from '@fortawesome/fontawesome-free-brands';

fontawesome.library.add(solid);
fontawesome.library.add(regular);
fontawesome.library.add(brands);