Duplicated CSS rules in production #46

mrksbnch · 2019-01-06T17:51:35Z

When using this CLI plugin, there are duplicated CSS rules when using CSS modules and the "composes" feature. This seems to be caused by the critical CSS that's inlined into the <head> and is both happening in development and production (main issue).

I've created the following test repo (https://github.com/mrksbnch/vue-ssr-css-issue) that I created using vue create (Vue router as the only feature) and vue add @akryum/vue-cli-plugin-ssr. Afterwards, I added a test.css file in the folder assets and composed (<style module>) two style declarations from that file in Home.vue and HelloWorld.vue.

You can see the duplicated rules after running npm run ssr:serve or npm run ssr:build and npm run ssr:start in the dev tools:

Both CSS rules are inlined on the server side (<style data-vue-ssr-id>):

This is just a simple test repo with only one CSS rule. In a proper app this will cause a lot (!) of duplicated CSS rules and increase the file size by quite a bit. I've tested it with a simple app and I noticed some rules being duplicated 5 or 6 times.

The text was updated successfully, but these errors were encountered:

zickat · 2019-02-07T12:47:15Z

I have the same issue, do you find a solution ?

p1n5u · 2019-02-08T13:06:26Z

Actually, the styles don't get added twice by the SSR plugin, but you get the styles delivered with the server side-rendered page and as soon as you mount the app on the client side on top of the pre-rendered dom, Vue adds the styles of the components again.
So it is not really a Bug or an Issue, but it is simply a reality of prerendering. Right now I am working on a solution to this (for example extract the CSS from the JS bundle and inject them into the HTML).
I keep you updated and tell you as soon as I've managed to solve this problem

p1n5u · 2019-02-08T13:33:25Z

The solution is really simple! The devs of vue-style-loader thought about this issue and already implemented a solution. To fix the duplicated style issue we simply need to configure the css loader to use the ssrId option:

ssrId (3.1.0+):
Type: boolean. Add data-vue-ssr-id attribute to injected <style> tags even when not in Node.js. This can be used with pre-rendering (instead of SSR) to avoid duplicate style injection on hydration.

To do this we simply need to add the loader config to our vue.config.js:

module.exports = {
  //...
  css: {
    loaderOptions: {
      css: {
        ssrId: true
      }
    }
  }
  //...
}

Hope it helps 😃

Alik2015 · 2019-05-08T04:35:18Z

Hi So just to confirm when using SSR the csss file is created as expected and the same content is also added to <style ssr-id>?

The ssrId:true does not stop this from happening.

le0l1 · 2019-05-08T05:22:21Z

+1

phiphan148 · 2019-06-03T11:35:49Z

The solution is really simple! The devs of vue-style-loader thought about this issue and already implemented a solution. To fix the duplicated style issue we simply need to configure the css loader to use the ssrId option:

ssrId (3.1.0+):
Type: boolean. Add data-vue-ssr-id attribute to injected <style> tags even when not in Node.js. This can be used with pre-rendering (instead of SSR) to avoid duplicate style injection on hydration.

To do this we simply need to add the loader config to our vue.config.js:
module.exports = {
  //...
  css: {
    loaderOptions: {
      css: {
        ssrId: true
      }
    }
  }
  //...
}
Hope it helps 😃

I tried but does not work. It still renders duplicated CSS

PidginEnemy · 2019-12-06T17:42:25Z

I have the same problem. vue-cli 3 + vue-cli-ssr-plugin (default config) + vue-apollo
In my production code i see folowing: https://cl.ly/0b20bf11baa4
My css rules duplicates multiple times (2 or 3 times)
I can't understand what's wrong and can't find docs...
I tried paste ssrId option to vue.config.js and get the folowing error:
ValidationError: Invalid options object. CSS Loader has been initialised using an options object that does not match the API schema. - options has an unknown property 'ssrId'.
@p1n5u maybe you know what i do wrong ?

Sporradik · 2020-01-28T23:00:03Z

@PidginEnemy @phiphan148

Those instructions that @p1n5u provided are perhaps a little bit misleading. vue-style-loader is not a supported loader for loaderOptions. See: https://cli.vuejs.org/config/#css-loaderoptions

There may be a way to get it to work like that, but I couldn't get it to work.

If you want to modify vue-style-loader options you can do so like this:

module.exports = {
	chainWebpack: config => {
		let types = ['vue-modules', 'vue', 'normal-modules', 'normal']
		types.forEach(type => {
			config.module.rule('css').oneOf(type).use('vue-style-loader').tap(options => {
				options.ssrId = true
				return options
			})
		})
	}
}

I was able to get the ssrIds working by doing this.

If you are using SCSS or similar things, you may have to do this multiple times replacing 'css' with the appropriate language. You can see someone modifying the vue-style-loader config like this here: vuejs/vue-style-loader#40

enriqg9 · 2020-04-10T02:23:31Z

@PidginEnemy @phiphan148

Those instructions that @p1n5u provided are perhaps a little bit misleading. vue-style-loader is not a supported loader for loaderOptions. See: https://cli.vuejs.org/config/#css-loaderoptions

There may be a way to get it to work like that, but I couldn't get it to work.

If you want to modify vue-style-loader options you can do so like this:
module.exports = {
	chainWebpack: config => {
		let types = ['vue-modules', 'vue', 'normal-modules', 'normal']
		types.forEach(type => {
			config.module.rule('css').oneOf(type).use('vue-style-loader').tap(options => {
				options.ssrId = true
				return options
			})
		})
	}
}
I was able to get the ssrIds working by doing this.

If you are using SCSS or similar things, you may have to do this multiple times replacing 'css' with the appropriate language. You can see someone modifying the vue-style-loader config like this here: vuejs/vue-style-loader#40

@Sporradik I followed with SCSS this but I am getting an error.

TypeError: Cannot set property 'ssrId' of undefined

Then if I initialize the options as shown on vuejs/vue-style-loader#40 I get:

Error: No loader specified

And if I specify a loader my build fails.

.use('vue-style-loader')
.loader('vue-style-loader')
...

SassError: SassError: expected "{".
  ╷
5 │ var content = require("!!../node_modules/cache-loader/dist/cjs.js??ref--0-0!../node_modules/vue-loader/lib/index.js??vue-loader-options!./App.vue?vue&type=style&index=0&lang=scss&");

Sylvadoc · 2020-04-24T10:57:48Z

Same issue with @enriqg9 :( I also try to add the data-vue-ssr-id boolean on style tags but it doesn't fix the duplication :(

cf https://github.com/vuejs/vue-style-loader#options

usedjimmy · 2020-04-24T14:01:33Z

you guys may want to take a look at this #158

enriqg9 · 2020-04-24T15:56:57Z

@usedjimmy thanks, that is a separate issue, already implemented that solution to avoid duplicate JS files.

This seems to be caused by the critical CSS that's inlined into the and is both happening in development and production (main issue).

emanuelverardi · 2020-07-05T20:48:26Z

Same issue with me. For some strange reason, when I mixed some 3'rd party lib's this stopped happening in one of my projects.
For all other projects using Vue Cli 3 and SSR I'm getting the css inline on the head of my html.
ex: <style data-vue-ssr-id="d2c949be:0 52a1d275:0"> css code here </style data-vue-ssr-id>.
The reason to use SSR is to have a good SEO and inlining the css jut make it terrible...
Anyone have any idea why this is happening ? Thanks.

sneko · 2020-07-08T09:00:30Z

Just to follow up... same for me since a long time. I don't get why by default we cannot have CSS extracted into separate files, but also even if I succeed doing that with some patchy settings, why they are rendered twice as you described.

It makes a pain to manage and to serve a proper website to visitors 😢 ...

Sporradik · 2020-07-09T00:05:48Z

@enriqg9 We don't use SCSS, so I'm not sure if I can be of much support, but I have some ideas of what you could try:

I would recommend taking a look at your built webpack config using vue inspect > output.js and then taking a look a the generated output.js file. It might give you some insight into the structure of your loaders and why it can't seem to find options for vue-style-loader under the scss rule.

Is it just throwing that error for scss or for css as well?

Is it possible that one of the "types" is not relevant in your case, so that is causing an error? If so, you could try removing it.

You could try only modifying options if they exist. If you can just prevent the error with an undefined check, then maybe it could work.

You can put console.logs in your chainWebpack function and they will log in the terminal where you run vue-cli-service start. It's a bit hard to read, but you could use this to figure out which type or rule is causing the error.

Webpack is very confusing to me, especially with vue-cli so I am sorry that I can't be of more help.

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Duplicated CSS rules in production #46

Duplicated CSS rules in production #46

mrksbnch commented Jan 6, 2019 •

edited

zickat commented Feb 7, 2019

p1n5u commented Feb 8, 2019 •

edited

p1n5u commented Feb 8, 2019

Alik2015 commented May 8, 2019 •

edited

le0l1 commented May 8, 2019

phiphan148 commented Jun 3, 2019

PidginEnemy commented Dec 6, 2019 •

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Sporradik commented Jan 28, 2020 •

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enriqg9 commented Apr 10, 2020 •

edited

Sylvadoc commented Apr 24, 2020

usedjimmy commented Apr 24, 2020

enriqg9 commented Apr 24, 2020

emanuelverardi commented Jul 5, 2020

sneko commented Jul 8, 2020 •

edited

Sporradik commented Jul 9, 2020 •

edited

Duplicated CSS rules in production #46

Duplicated CSS rules in production #46

Comments

mrksbnch commented Jan 6, 2019 • edited

zickat commented Feb 7, 2019

p1n5u commented Feb 8, 2019 • edited

p1n5u commented Feb 8, 2019

Alik2015 commented May 8, 2019 • edited

le0l1 commented May 8, 2019

phiphan148 commented Jun 3, 2019

PidginEnemy commented Dec 6, 2019 • edited

Sporradik commented Jan 28, 2020 • edited

enriqg9 commented Apr 10, 2020 • edited

Sylvadoc commented Apr 24, 2020

usedjimmy commented Apr 24, 2020

enriqg9 commented Apr 24, 2020

emanuelverardi commented Jul 5, 2020

sneko commented Jul 8, 2020 • edited

Sporradik commented Jul 9, 2020 • edited

mrksbnch commented Jan 6, 2019 •

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p1n5u commented Feb 8, 2019 •

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Alik2015 commented May 8, 2019 •

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PidginEnemy commented Dec 6, 2019 •

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Sporradik commented Jan 28, 2020 •

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enriqg9 commented Apr 10, 2020 •

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sneko commented Jul 8, 2020 •

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Sporradik commented Jul 9, 2020 •

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