Vite plugin legacy and detectModernBrowserCode check

[htavernier-ogoxe]

I every one,

I explore the code of the legacy plugin because I have to copy this behavior for a plugin between vite and symfony. https://github.com/lhapaipai/vite-bundle

I look more particularly at the portion that verifies if the browser supports modern code :

• <script type="module">
• import.meta
• dynamic import

the code is here :

vite/packages/plugin-legacy/src/index.ts

Line 114 in 697dd00

const detectModernBrowserCode = `try{import.meta.url;import("_").catch(()=>1);}catch(e){}window.${detectModernBrowserVarName}=true;`

// readable version
try {
    const metaUrl = import.meta.url;
    import("_").catch(() => 1);
} catch (e) {

}

window.__vite_is_modern_browser = true;

it looks like this code would set the variable __vite_is_modern_browser to true if the browser doesn't support : import.meta / dynamic import, which does not seem to be the desired behavior.

before opening an issue I would like to have your confirmation

[sapphi-red]

When import.meta or dynamic import is not supported, this code fails with a non-runtime SyntaxError. So the whole script won't be executed and __vite_is_modern_browser won't be set.

It seems the try-catch is redundant. I don't find any cases that throws an error.

[lhapaipai]

Thank you @sapphi-red for your answer !!