Startup.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.FileProviders;
using Swashbuckle.AspNetCore.Swagger;

namespace webapp
{
    public class Startup
    {
        // This method gets called by the runtime. Use this method to add services to the container.
        // For more information on how to configure your application, visit https://go.microsoft.com/fwlink/?LinkID=398940
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddMvc();
            services.AddSwaggerGen(c =>
            {
                c.SwaggerDoc("v1", new Info { Title = "webapp docs", Version = "v1" });
            });
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                app.UseStaticFiles(new StaticFileOptions()
                {
                    FileProvider = new PhysicalFileProvider(
                        Path.Combine(Directory.GetCurrentDirectory(), @"node_modules")),
                    RequestPath = new PathString("/vendor")
                });
            }
            
            app.UseStaticFiles();

            app.UseMvc();

            app.UseSwagger();
            app.UseSwaggerUI(c =>
            {
                c.SwaggerEndpoint("/swagger/v1/swagger.json", "main-spec");
            });
        }
    }
}