Question 1

How does preval.macro compare to babel-plugin-preval?

Accepted Answer

preval.macro is a wrapper around babel-plugin-preval that uses the babel-plugin-macros ecosystem for easier setup, but as noted in the README, babel-plugin-preval offers more APIs. Choose the macro for simplicity or the plugin for advanced features.

Question 2

How to integrate preval.macro with Create React App?

Accepted Answer

Since Create React App uses Babel internally, install preval.macro and babel-plugin-macros as dev dependencies, then ensure babel-plugin-macros is configured in your Babel settings, often via CRACO or ejecting for custom setup.

Question 3

Can preval.macro handle async operations or fetch data at build time?

Accepted Answer

Yes, it can execute async code during build, such as fetching static API data, but this requires the data to be available at compile time and won't update without a rebuild, limiting real-time adaptability.

Question 4

What build tools are compatible with preval.macro?

Accepted Answer

It works with any Babel-based setup, including Webpack and Rollup when configured with babel-plugin-macros. Tools like esbuild or SWC may not support it natively without Babel integration.

Question 5

How to use environment variables with preval.macro?

Accepted Answer

Access environment variables inside the preval tag, as they are available at build time, but note that changes require a rebuild and values are embedded statically, so avoid sensitive data exposure.

Question 6

Is preval.macro good for server-side rendering (SSR) optimizations?

Accepted Answer

It can precompute values for SSR by embedding data at build time, reducing runtime work, but ensure your Babel config supports both client and server builds to avoid inconsistencies.

Pre-evaluate code at buildtime

What is Pre-evaluate code at buildtime?

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