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Frequently Asked Questions

I can see HTML on my browser, but without any CSS​

There are a few reasons that you might not see CSS on the Jest Preview Dashboard (jest-preview):

  • Jest Preview generally uses Code Transformation to process CSS. You might forget to configure the transform in your Jest's config. Please see Installation for more. If you are using Create React App, you might want to visit CRA Example. If you are using Next.js, you might want to visit Next.js example.
  • If you already configure CSS transform, there is a very high chance that Jest is caching your CSS files. Please delete Jest's cache by running jest --clearCache.
  • You might have some CSS files that are not imported to your current testing component (i.e: src/index.jsx, src/main.jsx). You can configure global CSS by importing it in setupTests.js. See more at Installation.
// src/setupTests.js
import './global.css';
import '@your-design-system/css/dist/index.min.css';
import 'bootstrap/dist/css/bootstrap.min.css';
  • Your CSS strategy is not supported by Jest Preview yet. Please see Features for supported CSS strategies. Feel free to Request a new feature if you want Jest Preview supports your use case.
  • It might be a bug from Jest Preview. Let us know at Bug Report.

I couldn't use Automatic Mode​

Automatic Mode is in the experimental phase. If you are experiencing any issues when using Automatic Mode, please let us know at Jest Preview's GitHub issue. We appreciate your feedback and it would be super helpful for us to have a reproducible repository.

The preview does not reload automatically​

This is likely that you are using a Linux system. Please update jest-preview to the newest version (>= 0.2.8) to get the problem fixed. If it still persists, please help to report a bug with a minimum reproduction.

Global style of styled-components does not work?​

Since styled-components handles global style in Node.js environment and browser environment in different ways. So please see the work around at