Suggetion: allow to specify external's type (esm or commonjs)

[hronro]

Say we are trying bundle a module write in commonjs:

echo 'module.exports = require("bar").default + 100;' > foo.js
esbuild foo.js --bundle --format=esm --external:bar --platform=browser

The format of bar module is ESM and eventually we will made the bar module available in the browser using import-maps like this:

<script type="importmap">
{
	"imports": {
		"bar": "https://example.com/bar.js"
	}
}
</script>

However, currently esbuild will output something like __require("bar").default, which will cause a runtime error.

I guess esbuild is treating bar as a commonjs module, so using __require make sense.

So I wonder if we can specify the external's type, so esbuild will finally generate proper imports for the ESM externals.

If it's in a config file, it should be something like this:

{
    externals: ["foo", { name: "bar", type: "esm" }]
}

But I'm not sure how it could be done with a CLI argument.

[hronro]

After some thought, I think what I mentioned in #1927 might be better.

[watsonsong]

Is this suggestion has any solution?
I want to use esm but import some external with commonjs.