[feat] differential legacy builds by smertelny · Pull Request #2745 · sveltejs/kit

smertelny · 2021-11-04T23:25:07Z

Trying to solve #12 using @vitejs/legacy-plugin

I was testing it on examples/hn.svelte.dev and it is already working for IE11 with some configuration for svelte.config.js:

const config = {
    ...
    kit: {
	        legacy: {
			targets: ['ie >= 11'],
			additionalLegacyPolyfills: [
				'custom-event-polyfill',
				'core-js/modules/es.promise.js',
				'whatwg-fetch',
				'regenerator-runtime/runtime'
			]
		}
    ...
    }
}

BaseURI handwritten polyfill

There are several challenges I could not solve by myself:

Because of Safari 10.1 bug with executing nomodule code there is a problem with generated code for starting sveltekit app (import { start } from "/_app/start-[hash].js";), as Safari will execute this code anyway for both type="module" and nomodule scripts. Vite is adding some code checking for dynamic import support and for preventing Safari from executing nomodule scripts, but all scripts must be in separate js files (more on this in Safari nomodule gist and @vitejs/legacy-plugin) but start function execution is injected into html template.
While hydration in IE11 there is a bug that makes all elements "shuffle" on IE11 (it is better to see this). Was not trying to figure out this problem yet.
The process of finding the right polyfills is not very fast, but I did not want to "preset" something inside (because someone would like to target another browsers) and did not want to add polyfills.io like I saw in Sapper IE. It could be some setting in svelte.config.js file
I am not very strong in testing, so I will need some guidance if this draft will become something like PR.
Strange thing with pnpm-lock.yaml: after installing @vitejs/plugin-legacy +typescript@4.4.4 was deleted. Was it my bad?

Thank you for reading this wall of text =)

changeset-bot · 2021-11-04T23:25:09Z

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dishuostec · 2021-11-19T05:59:23Z

In my experimental implementation, I use a global init function for both module and nomodule.

Without legacy option:

Output:

<html>
	<head>
		...
		<link rel="modulepreload" href="/_app/start-45fd8323.js">
		<link rel="modulepreload" href="/_app/chunks/vendor-7bab4fb1.js">
		<link rel="stylesheet" href="/_app/assets/start-61d1577b.css">

		<script>
		window._sveltekit_init = (start, imt, nodes)=> {
			start({
				target: document.querySelector("#app"),
				paths: {"base":"","assets":""},
				session: {},
				host: location.host,
				route: true,
				spa: true,
				trailing_slash: "never",
				hydrate: null
			});
		}
		</script>
		<script type="module">
			import { start } from "/_app/start-45fd8323.js";
			window._sveltekit_init(start, m=>import(m), "");
		</script>
	</head>
	...
</html>

With legacy:

`defaults` and `not IE 11`

const config = {
  ...
  kit: {
    legacy: {
      targets: ['defaults', 'not IE 11']
    }
    ...
  }
}

Legacy polyfills:

{
  'core-js/modules/es.promise',
  'core-js/modules/es.array.iterator',
  'core-js/modules/web.dom-collections.iterator.js',
  'core-js/modules/es.typed-array.int32-array.js',
  'core-js/modules/es.typed-array.sort.js',
  'core-js/modules/es.string.replace.js',
  'core-js/modules/web.url.js',
  'core-js/modules/web.url-search-params.js'
}

Output:

<html>
	<head>
		...
		<link rel="modulepreload" href="/_app/start-45fd8323.js">
		<link rel="modulepreload" href="/_app/chunks/vendor-7bab4fb1.js">
		<link rel="stylesheet" href="/_app/assets/start-61d1577b.css">

		<script>
		window._sveltekit_init = (start, imt, nodes)=> {
			start({
				target: document.querySelector("#app"),
				paths: {"base":"","assets":""},
				session: {},
				host: location.host,
				route: true,
				spa: true,
				trailing_slash: "never",
				hydrate: null
			});
		}
		</script>
		<script type="module">
			import { start } from "/_app/start-45fd8323.js";
			window._sveltekit_init(start, m=>import(m), "");
		</script>
		<script type="module">!function(){try{new Function("m","return import(m)")}catch(o){console.warn("vite: loading legacy build because dynamic import is unsupported, syntax error above should be ignored");var e=document.getElementById("vite-legacy-polyfill"),n=document.createElement("script");n.src=e.src,n.onload=function(){(function(s,i){i(s.getAttribute('data-src')).then(function(m){window._sveltekit_init(m.start,i,s.getAttribute('data-nodes'))})})(document.getElementById('vite-legacy-entry'),function(m){return System.import(m)});},document.body.appendChild(n)}}();</script>
		<script type="nomodule">!function(){var e=document,t=e.createElement("script");if(!("noModule"in t)&&"onbeforeload"in t){var n=!1;e.addEventListener("beforeload",(function(e){if(e.target===t)n=!0;else if(!e.target.hasAttribute("nomodule")||!n)return;e.preventDefault()}),!0),t.type="module",t.src=".",e.head.appendChild(t),t.remove()}}();</script>
		<script type="nomodule" id="vite-legacy-polyfill" src="/_app/assets/polyfills-legacy.8548b1d0.js"></script>
		<script type="nomodule" id="vite-legacy-entry" data-src="/_app/legacy/start-81013b97.js" data-nodes="">(function(s,i){i(s.getAttribute('data-src')).then(function(m){window._sveltekit_init(m.start,i,s.getAttribute('data-nodes'))})})(document.getElementById('vite-legacy-entry'),function(m){return System.import(m)});</script>
	</head>
	...
</html>

`defaults` and `IE 11`

const config = {
  ...
  kit: {
    legacy: {
      targets: ['defaults', 'IE 11']
    }
    ...
  }
}

Legacy polyfills:

{
  'core-js/modules/es.promise',
  'core-js/modules/es.array.iterator',
  'core-js/modules/es.object.to-string.js',
  'core-js/modules/web.dom-collections.for-each.js',
  'core-js/modules/es.object.keys.js',
  'core-js/modules/es.array.slice.js',
  'core-js/modules/es.array.iterator.js',
  'core-js/modules/es.set.js',
  'core-js/modules/es.string.iterator.js',
  'core-js/modules/web.dom-collections.iterator.js',
  'core-js/modules/es.promise.js',
  'core-js/modules/es.typed-array.int32-array.js',
  'core-js/modules/es.typed-array.copy-within.js',
  'core-js/modules/es.typed-array.every.js',
  'core-js/modules/es.typed-array.fill.js',
  'core-js/modules/es.typed-array.filter.js',
  'core-js/modules/es.typed-array.find.js',
  'core-js/modules/es.typed-array.find-index.js',
  'core-js/modules/es.typed-array.for-each.js',
  'core-js/modules/es.typed-array.includes.js',
  'core-js/modules/es.typed-array.index-of.js',
  'core-js/modules/es.typed-array.iterator.js',
  'core-js/modules/es.typed-array.join.js',
  'core-js/modules/es.typed-array.last-index-of.js',
  'core-js/modules/es.typed-array.map.js',
  'core-js/modules/es.typed-array.reduce.js',
  'core-js/modules/es.typed-array.reduce-right.js',
  'core-js/modules/es.typed-array.reverse.js',
  'core-js/modules/es.typed-array.set.js',
  'core-js/modules/es.typed-array.slice.js',
  'core-js/modules/es.typed-array.some.js',
  'core-js/modules/es.typed-array.sort.js',
  'core-js/modules/es.typed-array.subarray.js',
  'core-js/modules/es.typed-array.to-locale-string.js',
  'core-js/modules/es.typed-array.to-string.js',
  'core-js/modules/es.array.sort.js',
  'core-js/modules/es.array.from.js',
  'core-js/modules/es.array.splice.js',
  'core-js/modules/es.function.name.js',
  'core-js/modules/es.string.starts-with.js',
  'core-js/modules/es.string.trim.js',
  'core-js/modules/es.array.concat.js',
  'core-js/modules/es.regexp.exec.js',
  'core-js/modules/es.string.split.js',
  'core-js/modules/es.array.filter.js',
  'core-js/modules/es.array.join.js',
  'core-js/modules/es.map.js',
  'core-js/modules/es.array.map.js',
  'core-js/modules/es.array.fill.js',
  'core-js/modules/es.string.anchor.js',
  'core-js/modules/es.regexp.to-string.js',
  'core-js/modules/es.string.replace.js',
  'core-js/modules/es.symbol.js',
  'core-js/modules/es.symbol.description.js',
  'core-js/modules/es.symbol.iterator.js',
  'core-js/modules/es.object.get-prototype-of.js',
  'core-js/modules/es.reflect.construct.js',
  'core-js/modules/es.reflect.get.js',
  'core-js/modules/es.object.get-own-property-descriptor.js',
  'core-js/modules/es.object.get-own-property-descriptors.js',
  'core-js/modules/es.object.assign.js',
  'regenerator-runtime/runtime.js',
  'core-js/modules/es.array.includes.js',
  'core-js/modules/es.string.includes.js',
  'core-js/modules/es.string.ends-with.js',
  'core-js/modules/web.url.js',
  'core-js/modules/web.url-search-params.js',
  'core-js/modules/es.string.search.js',
  'core-js/modules/es.array.find.js',
  'core-js/modules/es.object.entries.js',
  'core-js/modules/es.number.constructor.js',
  'core-js/modules/es.string.match.js'
}

Output:

<html>
	<head>
		...
		<link rel="modulepreload" href="/_app/start-45fd8323.js">
		<link rel="modulepreload" href="/_app/chunks/vendor-7bab4fb1.js">
		<link rel="stylesheet" href="/_app/assets/start-61d1577b.css">

		<script>
		window._sveltekit_init = (start, imt, nodes)=> {
			start({
				target: document.querySelector("#app"),
				paths: {"base":"","assets":""},
				session: {},
				host: location.host,
				route: true,
				spa: true,
				trailing_slash: "never",
				hydrate: null
			});
		}
		</script>
		<script type="module">
			import { start } from "/_app/start-45fd8323.js";
			window._sveltekit_init(start, m=>import(m), "");
		</script>
		<script type="module">!function(){try{new Function("m","return import(m)")}catch(o){console.warn("vite: loading legacy build because dynamic import is unsupported, syntax error above should be ignored");var e=document.getElementById("vite-legacy-polyfill"),n=document.createElement("script");n.src=e.src,n.onload=function(){(function(s,i){i(s.getAttribute('data-src')).then(function(m){window._sveltekit_init(m.start,i,s.getAttribute('data-nodes'))})})(document.getElementById('vite-legacy-entry'),function(m){return System.import(m)});},document.body.appendChild(n)}}();</script>
		<script type="nomodule">!function(){var e=document,t=e.createElement("script");if(!("noModule"in t)&&"onbeforeload"in t){var n=!1;e.addEventListener("beforeload",(function(e){if(e.target===t)n=!0;else if(!e.target.hasAttribute("nomodule")||!n)return;e.preventDefault()}),!0),t.type="module",t.src=".",e.head.appendChild(t),t.remove()}}();</script>
		<script type="nomodule" id="vite-legacy-polyfill" src="/_app/assets/polyfills-legacy.7b89e3e3.js"></script>
		<script type="nomodule" id="vite-legacy-entry" data-src="/_app/legacy/start-81013b97.js" data-nodes="">(function(s,i){i(s.getAttribute('data-src')).then(function(m){window._sveltekit_init(m.start,i,s.getAttribute('data-nodes'))})})(document.getElementById('vite-legacy-entry'),function(m){return System.import(m)});</script>
	</head>
	...
</html>

vercel · 2021-12-03T11:58:38Z

@smertelny is attempting to deploy a commit to the Svelte Team on Vercel.

A member of the Team first needs to authorize it.

bfanger · 2022-01-16T09:13:41Z

packages/kit/package.json

 	"type": "module",
 	"dependencies": {
 		"@sveltejs/vite-plugin-svelte": "^1.0.0-next.30",
+		"@vitejs/plugin-legacy": "^1.6.2",


Could @vitejs/plugin-legacy become an optional dependency?
That would keep the installation fast for non legacy projects

Tal500 · 2022-07-25T21:18:12Z

2. While hydration in IE11 there is a bug that makes all elements "shuffle" on IE11 (it is better to see this). Was not trying to figure out this problem yet.=

See my bug report sveltejs/svelte#7723 and the PR which fixes it sveltejs/svelte#7724.
At least one thing can be easily fixed :-)

Tal500 · 2022-07-26T11:00:27Z

packages/kit/src/runtime/client/renderer.js

 	 *   Root: CSRComponent;
 	 *   fallback: [CSRComponent, CSRComponent];
-	 *   target: Node;
+	 *   target: Element;


why needed?

#12: Initial commit for differential legacy builds implementation

4d60069

benmccann changed the title ~~#12: Initial commit for differential legacy builds implementation~~ [feat] differential legacy builds Nov 5, 2021

dominikg mentioned this pull request Dec 1, 2021

Legacy builds #2953

Closed

3 tasks

Extracting page data to its own variable; fixes after extraction of data

b6c04c1

bluwy mentioned this pull request Dec 4, 2021

feat: export constants from @vite/plugin-legacy vitejs/vite#5948

Closed

bfanger reviewed Jan 16, 2022

View reviewed changes

perqa mentioned this pull request Mar 20, 2022

Differential legacy builds #12

Open

Tal500 mentioned this pull request Jul 25, 2022

Legacy support issue in IE11 on hydration sveltejs/svelte#7723

Closed

Tal500 reviewed Jul 26, 2022

View reviewed changes

Tal500 mentioned this pull request Aug 25, 2022

feat: legacy JS support #6265

Closed

5 tasks

smertelny closed this Apr 17, 2023

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[feat] differential legacy builds#2745

[feat] differential legacy builds#2745
smertelny wants to merge 2 commits intosveltejs:masterfrom
smertelny:legacy-builds

smertelny commented Nov 4, 2021

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Tal500 commented Jul 25, 2022

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smertelny commented Nov 4, 2021

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dishuostec commented Nov 19, 2021

Without legacy option:

With legacy:

defaults and not IE 11

defaults and IE 11

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bfanger Jan 16, 2022 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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`defaults` and `not IE 11`

`defaults` and `IE 11`

bfanger Jan 16, 2022 •

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