sidvishnoi / esm-to-cjs Goto Github PK

Hello, I encountered some problems while experiencing the conversion function

case 1 Import only is not supported

// input
import "lib";

// what i wanted
require("lib");

// actual：ParseError

case 2 Single and double quotation marks should be mixed

// input
import mod from "mod";
import foo from 'foo';

// what i wanted
const mod = require("mod");
const foo = require("foo");

case 3 export mix

// input
export function foo(){}
exports.bar = function (){}

// what i wanted
function foo(){}
exports.bar = function (){}
exports.foo = foo;

// actual
function foo(){}
exports.bar = function (){}
module.exports = { // covered
  foo
};

Would be cool to have typings for this lib

I came to your interesting package in searching of a lighter esm to cjs transformer.

But I noticed the code is semantically wrong which can lead to logic error.

Your example

// input
import { resolve as resolvePath } from "path";
resolvePath("./hello")

// what i wanted
const {  resolve: resolvePath } = require("path");
resolvePath("./hello")

Translated the esm import to a simple variable, this is wrong in esm semantic. There is a reason why all babel/TS transforms esm import into verbose a_namespace.an_exported_name, because in esm standard, the import does not create a local JS variable, it's a read-only property on the namespace of that esm module.

Consider following proof, create two local files:
foo.mjs

let foo = 1;
function increaseFoo() {
  foo += 1;
}
export { foo, increaseFoo };

index.mjs

import { foo, increaseFoo } from './foo.mjs';
console.log('foo is ' + foo);
increaseFoo();
console.log('foo is ' + foo);

Then use nodejs v12 or above

node --experimental-modules index.mjs

It prints out:

foo is 1
foo is 2

You can see that foo inside index.mjs is not a local variable, otherwise it cannot be mutated.