[BUG] mobx: Unexpected "@"

[mogiihu]

Bug Report Quick Checklist

• ✅ I am on the latest version of Snowpack & all plugins.(3.3.7)
• ✅ I use package manager npm.
• ✅ I run Snowpack on OS Mac.
• ✅ I run Snowpack on Node.js v12+(v14.16.1)

Describe the bug

When I use mobx's decorator in the file, I get an error.

[16:34:25] [snowpack] Error: Transform failed with 1 error:
/project/react-snowpack3/src/pages/todoView/index.jsx:4:0: error: Unexpected "@"
[16:34:25] [@snowpack/plugin-esbuild] [500] /src/pages/todoView/index.js
A quick, clear, concise summary of what the bug is.

Expected behavior

Support for decorator.

[drwpow]

Hi @mogiihu. Decorators are currently a Stage 2 proposal which means they’re technically not JavaScript, which means you have to transform your JS in order to use them. By default, Snowpack does not support experimental JS features, because there are differing opinions on how they should be transformed (again, because it’s not yet implemented).

Two temporary workarounds for now are to either use TypeScript for decorators because of esbuild’s support, or use @snowpack/plugin-babel to load Babel plugins to transform decorators.

I’m going to close the issue because we won’t provide support for this, but please let me know if either of the workarounds are sufficient for you.