Writing JavaScript without a build system

Re:Writing JavaScript without a build system by mtlynch on Thursday February 16, 2023 @08:01PM (#34829243)

Ah, gotcha. Thanks!

>I generally don't consider installing from npm a build step. I also don't really consider rewriting import specifiers a build step - it's just locating files on disk.

Sorry, maybe this is just my JS ignorance, but I don't understand how this runs without a build step.

If I run npm -i lit, it puts lit into node_modules. But then if I put "import {LitElement, html} from 'lit';" into a JS file and run a dumb static webserver (like python3 -m http.server), what's linking "from 'lit'" to the necessary files in node_modules?

I just tried running the first tutorial[0] verbatim after npm installing lit to the same directory, and I get:

  Uncaught TypeError: The specifier “lit” was a bare specifier, but was not remapped to anything. Relative module specifiers must start with “./”, “../” or “/”. my-element.js:1:31

I'd love to use this, I'm just not following how this works.

Is it designed to run server-side rather than for static sites?

[0] https://lit.dev/tutorials/intro-to-lit/

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Re:Writing JavaScript without a build system by TimTheTinker on Thursday February 16, 2023 @08:22PM (#34829411)

Looks like you need a <script type="importmap"> -- it could map 'lit' to the CDN hosted version or to a relative path.

More info: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/sc...

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Re:Writing JavaScript without a build system by mtlynch on Thursday February 16, 2023 @08:25PM (#34829438)

Ah, thanks! I'd never encountered these before.

It seems like a handy way to make my code match the code in documentation that assumes a Node environment.

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Re:Writing JavaScript without a build system by TimTheTinker on Thursday February 16, 2023 @08:42PM (#34829562)

No problem! There's also a polyfill if you need to support Safari:

https://github.com/guybedford/es-module-shims

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Re:Writing JavaScript without a build system by chrisehlee on Saturday February 18, 2023 @12:42AM (#34844265)

Thankfully iOS 16.4 will be natively supporting import maps so fingers crossed this might be easier soon

https://webkit.org/blog/13878/web-push-for-web-apps-on-ios-a...

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Re:Writing JavaScript without a build system by e111077 on Thursday February 16, 2023 @08:27PM (#34829450)

When one writes `import 'lit'` the browser doesn't know where Lit is. This is called a bare module specifier vs an absolute import specifier:

  import '/home/user/project/node_modules/lit/index.js'

A relative specifier:

  import '../node_modules/lit/index.js'

Or a URL Specifier:

  import 'https://unpkg.com/lit?module'

So you have four-ish options to tell the browser where to look for 'lit':

1. Use a server that will use the node module resolution algorithm and transforms it to a relative specifier as it encounters the import (transform/build-ish?)

2. Use experimental "import maps" to go fully buildless to tell the browser where to point that bare module to (buildless)

3. Bundle all your code (build step)

4. Use a bundle from a CDN

Here are some examples of each:

Server that transforms import specifiers (lit.dev does this by default):

https://lit.dev/playground/#gist=9092862a77acf73dd1e6faa73a3... (build-ish)

Import Maps (2):

https://lit.dev/playground/#gist=0c4f66396b333c82cb27e7dd3b2... (buildless)

https://lit.dev/playground/#gist=91c0b286698612b013eb81881ff... (build-ish)

Url Specifiers (2):

https://lit.dev/playground/#gist=05655736300f0425644e61a6264... (buildless)

https://lit.dev/playground/#gist=6d23e8e8dadacd7488bdec81d0f... (build-ish)