[SSR] context.styles is undefined when runInNewContext !== true

[nekuz0r]

Version

2.4.2

Reproduction link

https://github.com/nekuz0r/vuejs-ssr-styles-issue

Steps to reproduce

npm run build
npm run start

What is expected?

context.styles to be defined

What is actually happening?

context.styles is undefined when runInNewContext is equal false or 'once'

---

context.styles getter is not set on the new context created when
runInNewContext is equal to false or once.

vue-style-loader is defining a getter for context.styles property
(https://github.com/vuejs/vue-style-loader/blob/master/lib/addStylesServer.js#L9)

When runInNewContext is false or once, VueJS is copying the _styles
property in userContext from initialContext but the styles getter is not.
(

vue/src/server/bundle-renderer/create-bundle-runner.js

Line 131 in 8ff77a2

userContext._styles = deepClone(initialContext._styles)

)

Adding the following line after that one fixes the issue

Object.defineProperty(userContext, 'styles',
  Object.getOwnPropertyDescriptor(initialContext, 'styles')
)

[JounQin]

@yyx990803 It's a typo which makes styles not enumerable, it should be fixed after the PR merged.

[yyx990803]

@JounQin are you sure? Even if it's not enumerable it should still be present. (I haven't got time to properly investigate this issue yet)

[JounQin]

Ah, sorry I read it wrong, and as I know it should not be an issue here, I'll try to figure it later.

I used to extract all styles of first chunk into .css, and also if there is another async chunk it will generate styles property correctly, so I haven't encountered this problem.

However,

Object.defineProperty(userContext, 'styles',
  Object.getOwnPropertyDescriptor(initialContext, 'styles')
)

sounds not good to me, because context in customContext getter will always be initialContext.