docs: warning for new URL(url, import.meta.url)

[gaomeng1900]

Vite use es2019 as default esbuild target for building and pre-bundling, which does NOT support import.meta.url.

new URL(import.meta.url) will be transpiled to

var import_metaN = {};
new URL(url, import_metaN.url);

This will cause a fatal error.

Description

fix #5558 and #5270

new URL(url, import.meta.url) pattern does not work by default. Users will get a confusing error after the code is bundled.

Additional context

I would recommend vite to upgrade its esbuild config. Even esbuild use es2020 by default.

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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