import a c or js module and print it, show exception in quickjs

[1DumbCicada]

i just print an outside module

**test_fib.js**

import * as os from "qjs:os";

const isWin = os.platform === 'win32';
// const { fib } = await import(`./fib.${isWin ? 'dll' : 'so'}`);
import(`./fib.${isWin ? 'dll' : 'so'}`).then(
    (res)=> {
        console.log('quickjs env', res)
    }
)

but show an exception tag

PS D:\Quickjs\build> ./qjs.exe test_fib.js
quickjs env <exception

then i test in node env

**es_li.mjs** 

export function hello() {
    
}

**test_fib.js**
import("./es_li.mjs").then(
    (res) => {
        console.log('node env', res)
    }
)

it is ok

PS D:\Quickjs\build> node test_fib.js
node env [Module: null prototype] { hello: [Function: hello] }

[saghul]

What the x period you get?

[bnoordhuis]

The example can be simplified to qjs -e 'import("./fib.so").then(print)' - i.e., trying to print a module object.

Module objects cannot be coerced to strings, that's why it prints <exception>. The qjs REPL handles it gracefully, by the way; it inspects the object, it doesn't try to stringify it.

I don't think we want to duplicate the logic from repl.js in quickjs-libc.c and neither do we want to give module objects .toString or .valueOf methods (because that's almost guaranteed to be a spec violation; what if a module exports a toString method?)

Maybe the best we can do is update print() and console.log() to use object[Symbol.toStringTag] when normal stringification fails.