fs(js): impl uses cjs format

[PrairieFire2b]

The JS implementation of fs module uses require("fs") directly, but MoonBit compiler supports not only cjs format, but also esm and iife.

x/fs/fs_js.mbt

Line 18 in 6edf9b1

#| var fs = require('fs');

x/fs/fs_js.mbt

Line 32 in 6edf9b1

#| var fs = require('fs');

[Lampese]

Are you saying that if this library is exported with ESM and IIFE, it may cause some problems? I think the cost of doing this support is relatively high, and to some extent, packaging tools (such as webpack esbuild) can smooth out this difference

[PrairieFire2b]

But this is essentially a bug and should be fixed. And the additional build process might introduce unnecessary complexity?

[Lampese]

But this is essentially a bug and should be fixed. And the additional build process might introduce unnecessary complexity?

But what are the possible solutions, judging the user's desired import method from the configuration file? That doesn't sound good.

I think there are two separate questions here:

• Is using require("fs") actually incorrect or broken when targeting ESM / IIFE, or is it just suboptimal?
• If it is incorrect, should MoonBit itself handle this, or should it be left to bundlers?