When do we npm install to dependencies?

[manuganji]

Is every package installed as a dev dependency with npm i -D <package> because svelte is compiled? In what cases will we do npm i <package>?

EDIT: Sorry, I couldn't find a concrete answer from my reading. If this has been answered elsewhere, I'd like to know. I'm trying to understand compiled nature of svelte better.

[furudean]

There is no meaningful heuristic between devDependencies and dependencies when it comes to Svelte Kit. Dependencies are tree-shaken at build time, meaning that modules are only included in your build bundle if they are actually used in your code.

However I find it easier to visually grep what's used for what in my package.json by making anything that is used at runtime a dependency and anything else a devDependency.

[elliott-with-the-longest-name-on-github]

@furudean If I remember correctly, there's some special case of this with adapter-node (or there was at some point?). I specifically remember having to move some node-only dependencies from devDependencies to dependencies in order to be able to build. But it was like six or eight months ago, so it may have just been a bug.

[hyunbinseo]

{
  "devDependencies":{
    "@sveltejs/adapter-auto":"workspace:*",
    "@sveltejs/kit":"workspace:*",
    "svelte":"^3.44.0",
    "svelte-preprocess":"^4.9.8",
    "typescript":"~4.6.2"
  },
  "dependencies":{
    "@fontsource/fira-mono":"^4.5.0",
    "@lukeed/uuid":"^2.0.0",
    "cookie":"^0.5.0"
  }
}

create-svelte's default template does distinguish devDependencies and dependencies.

[samlfair]

A colleague pointed out to me that:

Since SvelteKit allows you to package your lib folder for reusability, you should install such "runtime" dependencies as dependencies so that they don't get bundled with the hypothetical package, but still installed alongside. This would allow projects relying on such package to benefit from updates matching the semver range specified for such dependencies without the need for a republish.

If you're publishing your app as a package, that's a good argument for installing packages as dependencies.