Objects from imported modules have different core types, making instanceof useless

[phorks]

The instanceof operator always returns false when used with the values from imported modules.

const moduleFromString = require("module-from-string");

const code = "throw new Error();";

try {
  const x = moduleFromString.requireFromString(code);
} catch (err) {
  console.log(Object.getPrototypeOf(err).name === Error.prototype.name);
  console.log(err instanceof Error);
  console.log(err instanceof Object);
}

It outputs:

• true
• false
• false

Or:

const moduleFromString = require("module-from-string");

const code = "exports.obj = {}";

const x = moduleFromString.requireFromString(code);
console.log(Object.getPrototypeOf(x.obj).name === Object.prototype.name);
console.log(x.obj instanceof Object);

Outputs:

• true
• false

Using importFromString yields the same results. It's a side effect of using runInNewContext instead of runInThisContext (or providing context in case of the vm.Module). If this behavior is not intentional, I would be glad to fix it.

[exuanbo]

This is intentional, but I have added an option useCurrentGlobal and some factory functions createRequireFromString etc. in the pre-released version 3.2.0-0. You can install it and give it a try.

If it works well, I will update the README and publish a new minor version tomorrow.

[exuanbo]

Please use the newly added option useCurrentGlobal in 3.2.0.

[phorks]

Thank you. Just a question about the implementation though, did you consider the compileFunction approach that the default nodejs cjs loader takes (here)? That way, there would be no need to shallow copy the entire global object each time.

[exuanbo]

Thank you for the suggestion, I haven't actually considered this approach.

I will try refactoring the code in the next few days.