Some doubts about `NWESM`

[ssnangua]

OS: win32 x64 10.0.19045
NW: 0.99.1

Q1

What does the NWESM switch do? The new version of NW.js seems to be able to load ES modules in Node context without enabling NWESM:

package.json:

{
  "name": "nwesm-test",
  "main": "main.js"
}

main.js:

const testMJS = require("./test.mjs");
console.log(testMJS);

nw.Window.open("./index.html");

test.mjs:

export default {
  test: "test",
};

Q2

DevTools crashes when NWChainImportNode is enabled

package.json:

{
  "name": "nwesm-test",
  "main": "index.html",
  "chromium-args": "--enable-features=NWESM,NWChainImportNode"
}

Q3

Loading ES module via import in node-main will cause an error:

package.json:

{
  "name": "nwesm-test",
  "main": "index.html",
  "node-main": "node-main.js"
}

node-main.js:

import testMJS from "./test.mjs";
console.log(testMJS);

Q4

Why not add type="module" when loading main and bg-script, so that we can use import in these two scripts?

[rogerwang]

NWESM tells the V8 engine to use the module resolver in Node.js. Without it, you are using the module resolver in Browser, which may work in some cases, but obviously it can't load Node.js modules like 'fs' ... See the issue linked in the change log for more discussion, as well as the official document:

#7639
https://nwjs.readthedocs.io/en/latest/References/Command%20Line%20Options/#-enable-featuresnwesm

[rogerwang]

Loading ES module via import in node-main will cause an error:

This is expected since you didn't enable NWESM.

[ssnangua]

Loading ES module via import in node-main will cause an error:

This is expected since you didn't enable NWESM.

Thanks for your reply.
I enabled NWESM, but it still causes the same error.

[rogerwang]

I enabled NWESM, but it still causes the same error.

this issue was just fixed in git.

[rogerwang]

Why not add type="module" when loading main and bg-script, so that we can use import in these two scripts?

This could have some side effect and potentially breaks apps, e.g.

• Each module has its own top-level scope. Variables, functions, and classes declared at the top level of a module are local to that module by default. They are not automatically added to the global ( window ) object.
• this is undefined: At the top level of a module, this is undefined, unlike in classic scripts where it refers to the global object (window in browsers).
• Automatic Strict Mode: All code within a <script type="module"> is automatically in "strict mode."

[ssnangua]

Why not add type="module" when loading main and bg-script, so that we can use import in these two scripts?

This could have some side effect and potentially breaks apps, e.g.

• Each module has its own top-level scope. Variables, functions, and classes declared at the top level of a module are local to that module by default. They are not automatically added to the global ( window ) object.
• this is undefined: At the top level of a module, this is undefined, unlike in classic scripts where it refers to the global object (window in browsers).
• Automatic Strict Mode: All code within a <script type="module"> is automatically in "strict mode."

Got it, thanks for your reply.

This issue will be closed after the version with fix Q2 & Q3 is released.