Vite FAQ

About 2 min

Slow in a cold boot with Vite

This is the expect behaviour. We are adding more features, which means we have 2× to 8× lines of code comparing with @vuepress/theme-default according to the functions you are using. So transpiling and sending the theme and plugins code to broswer is expected to increase from 0.8s - 2s in @vuepress/theme-default to 3s - 10s (range due to machine performance).

Tree-shaking burden

In order to fully support Tree-shaking in functionality and styles, themes and plugins do additional work, including modularization, partial injection, generation of temp files, etc. These extra behaviors ensure that unused feature code is removed at build stage, but it also means that more logic needs to be performed and more fragmented files need to be loaded in development mode.

Dude, you can't expect to have the full power of tree-shaking support and still be extremely fast when the development server starts up, they are contradictory.

style system

In order to make component styles binding with component, we split the styles according to the component hierarchy and imported them in components, which greatly slowed down the speed.

  • @vuepress/theme-default is placing all the styles together at styles folder and importing them entirly, so that sass will only need to compile once and vite only need to send 1 extra web request. That’s why it’s fast.

    But this will let style unbinded with components, and they will be injected anyway. So that when you override a component or a layout, you have to override old styles to build styles you want.

  • vuepress-theme-hope is binding styles with components, but that means sass has to compile styles for each component, and vite need to send an extra request for each components. Due to vuepress-theme-hope has 2× to 6× components (depending on whether you enable blog featues or not) comparing with @vuepress/theme-default, it will take extra time of 2.4s - 4s for that.

    But, you can easily override a component together with it’s styles in this way.

So, due to the above reasons, vuepress-theme-hope will have an average of 4× code and 10× requests comparing with @vuepress/theme-default, so the time increasing from 2s to 10s is reasonable and expected.

No effect on HMR and online speed

Don't worry, the above extra overhead mainly exists in code boot. Due to the large size of the unoptimized code in the development environment, the corresponding time will also increase after refreshing.

  • These extra overheads do not affect HMR, so when editing the Markdown file, the page's HMR response can still remain at the 100 ms level.

  • Unused code twill be removed during the build phase with well design, so the production environment usually only adds additional 200 KB - 500 KB size in JS entry comparing the default theme and about 100 ms of extra script execution time, so the online impact is very small.

@import() in CSS does not work

In VuePress2, importing web CSS via @import in index.scss has no effect. You may need to manually import it in the head option of your VuePress configuration.

Reason

  1. CSS imported via @import in Sass will be compiled into standard CSS @import syntax.
  2. The CSS @import syntax only works at the top of css file.
  3. To give user styles a higher priority, we will import user styles after theme and plugin styles.
  4. During vite builds VuePress2 app, all styles are compressed into a single CSS file.

The above results in the user’s CSS @import imports in Sass appearing in the middle of the final CSS file and thus invalid.

The default theme also has the same problem, and this cannot be fixed on the theme side.

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