Sapper Svelte Review


#sapper, #svelte, #staticgenerators

During the winter holidays I always take some time to explore new technologies.

In my previous post I have questioned the utility of static sites generators in 2020. It turns out that static websites are now a big thing and as you can see on Jamstack there are several solutions to create a static website. After spending some hours with cobalt (a static site generator built in rust) I had almost concluded my experiment before stumpling upon Sapper.

According to the website:

"Sapper is a framework for building web applications of all sizes, with a beautiful development experience and flexible filesystem-based routing.

Unlike single-page apps, Sapper doesn't compromise on SEO, progressive enhancement or the initial load experience β€” but unlike traditional server-rendered apps, navigation is instantaneous for that app-like feel."

My adventure started with their tutorial which is pretty straightforward. I soon realised that whilst sapper an export to a static website, is not really working out well for a traditional static stack as it expects JSON data, probably from a headless CMS.

But fear not, I have found a blog template that parses markdown articles. Credits to the author (joshnuss on github) for posting even 2 screencasts on how to deal with it.

I did manage to export a blog as a static website. The technology of Svelte is similar to React and Vue yet is not: it is more akin to language in its own right and the syntax is, in my opinion, way better than the other front end frameworks.

So there seems to be a great community behind the project which is great. This said I run into a number of issues: You can't use CSS easily (well you can write it under style but forget including a CSS easily and using it to style elements) this for me was a bit of a letdown. But this issue couldn't win with my enthusiasm for this new technology.

I didn't give up so I stumbled upon the very cool Carbon Components Svelte from IBM. With a bit of effort (and no prior knowledge of Svelte or Sapper) I did manage to integrate it.

import "carbon-components-svelte/css/g10.css";
import * as sapper from '@sapper/app'

  target: document.querySelector('#sapper')
 in client.js


import {
} from "carbon-components-svelte";

let isSideNavOpen = false;

  import Notification20 from "carbon-icons-svelte/lib/Notification20";
  import UserAvatar20 from "carbon-icons-svelte/lib/UserAvatar20";
  import AppSwitcher20 from "carbon-icons-svelte/lib/AppSwitcher20";
  import { getContext } from "svelte";


<div slot="skip-to-content">
  <SkipToContent />

  <HeaderNavItem href="/about" text="About" />
  <HeaderNavItem href="/contribute" text="Contribute" />
  <HeaderNavItem href="/learnhtml" text="Learn Html" />


<SideNav bind:isOpen={isSideNavOpen}>
  <SideNavLink href="/about" text="About"  />
  <SideNavLink href="/contribute" text="Contribute"  />
  <SideNavLink href="/learnhtml" text="Learn Html" />
header.svelte notice the svelte syntax

and the posts:

  export let posts



  ul {
    margin: 0;
    padding: 0;


font-family: corporate-s, sans-serif;
font-weight: 700;
font-style: normal;

  /* clearfix */
  ul::after {
    content: '';
    display: block;
    clear: both;

  li {
    display: block;
    float: left;

  [aria-current] {
    position: relative;
    display: inline-block;

  [aria-current]::after {
    position: absolute;
    content: '';
    width: calc(100% - 1em);
    height: 2px;
    background-color: rgb(255,62,0);
    display: block;
    bottom: -1px;

  a {
    text-decoration: none;
    padding: 1em 0em;
    display: block;

  figure {


  img {
  margin: 1 1 1em 0;
width: 5%;
  max-width: 400px;
  margin:0;padding: 0;


{#each posts as post}
    <a href={`${post.permalink}`}>


and the index 

  import PostList from '@/components/PostList.svelte'
  import rilla from 'images/HTML5.svg';
  import {posts} from '@/posts'

  h1, figure, p {
    text-align: center;
    margin: 0 auto;

  figure {
    margin: 0 0 1em 0;

  img {
    width: 10%;
    max-width: 400px;
    margin: 0 0 1em 0;

  p {
    margin: 1em auto;

  @media (min-width: 480px) {
    h1 {
      font-size: 4em;


<h2> <b> Welcome to HTML.DEVπŸ‘</b>  </h2>

<PostList {posts}/>

Unfortunately the Carbon Components Svelte would add 430K or more of CSS: so once I exported my shiny new test website into a static site I received a 43% score by Google Pagesped insight. This was both weird and surprising because in other websites, where I use bootstrap or in any case failry big CSS files, I never received less than 90% (for a small, simple website like this on).

Styling apart (I am sure that other components like material might work btter): I just don't see myself writing a post in markdown, build and then upload it on my static hosting. Is just a very tedious workflow vs simply typing your article in a gorgeous online interface, click save and watch it live on your webiste. It is just not convenient and not modern.

Nota bene: Speed benefit of static (via Nginx) or Express was zero. As a matter of fact the Express+DB website was faster than the static sapper website (benchmarked with apache benchmark 10000 requests, 100 concurrent).

Even when trying a more classic generator (like cobalt rs) I have spent a few hours fighing with their variables (not so static after all ?!) so I still think that online CMS are still the way to go. I am also not persuaded at all by these system that create javascript that generates HTML. Clearly many apps can benefit from it but I don't see how a CMS/blog system would make the pubishing flow better. I still find the concept intriguiding (especially for websites that don't run many updates) but for now a static website is not for me. πŸš„