(dynamic import) transform should probably respect format: esm

[egoist]

When using with options { target: 'node12', format: 'esm' }, dynamic import is transformed to require:

> require('esbuild').transformSync(`import('foo')`,{target:'node12',format:'esm'})
{
  warnings: [],
  code: '...omitted...
    'Promise.resolve().then(() => __toModule(require("foo")));\n',
  map: ''
}

this would break rollup-plugin-esbuild since rollup only recognizes es module by default.

esbuild: 0.11.10

[evanw]

Well dynamic import doesn't work in node 12, so this transformation is correct. Someone explicitly asked for this transformation to be added in #1084. Node 12 is no longer actively maintained and is now in maintenance mode. If you don't actually need to support node 12, the easiest solution here could just be to use target: 'node13.2' instead, which is the earliest version of node that supports this feature according to MDN.

Technically node shipped a back-ported version of node 12.x that does work with dynamic import, node 12.20+. So in theory this could be made to work by using target: 'node12.20' and then changing esbuild to mark node12.20 as supporting dynamic import. However, esbuild currently doesn't support a feature becoming unsupported and re-supported as the version number increases, so support for discontiguous version ranges would have to be added to esbuild first. See #1084 for more context.

[lukeed]

It could be agreeable to pretend like all of Node 13.x didn't exist, though. For example, it included a different/incomplete "exports" resolution algorithm up until (and including) 13.7.

It's been a mess, tbh. Fun stuff.

[egoist]

👍 Sounds fair.