Is that `Array.prototype.concat` will be removed during importing polyfilll? #1034

aleen42 · 2022-01-05T08:34:31Z

Recently, I have found that if I have shimmed Function.prototype.bind at first:

var $A = Array.from = function (iterable) {
    if (!iterable) return [];
    if (iterable.toArray) {
        return iterable.toArray();
    } else {
        var results = [];
        for (var i = 0; i < iterable.length; i++)
            results.push(iterable[i]);
        return results;
    }
};

Function.prototype.bind = function () {
    var __method = this, args = $A(arguments), object = args.shift();
    return function () {
        return __method.apply(object, args.concat($A(arguments)));
    };
};

And then, when running in the process of importing core-js/shim, Array.prototype.concat has been removed, and an exception was thrown when core-js tries to call shimmed Function.prototype.bind.

I just want to confirm whether it is due to the commit (277cb33), which wants to protect some built-in methods?

The text was updated successfully, but these errors were encountered:

zloirock · 2022-01-05T09:44:51Z

Is that Array.prototype.concat will be removed during importing polyfill?

Only in case if it should be polyfilled and immediately will be replaced to the proper method.

And then, when running in the process of importing core-js/shim, Array.prototype.concat has been removed, and an exception was thrown when core-js tries to call shimmed Function.prototype.bind.

I can't reproduce that. I see only some possible issues from your incomplete .bind implementation that does not work with constructors.

zloirock · 2022-01-05T09:50:29Z

For example, your code, core-js import and core-js test case:

Issues only in your .bind since core-js does not detect such cases of broken in the userland environment, Array.from is replaced to the proper. Nothing related to .concat.

aleen42 · 2022-01-05T10:27:55Z

In my case, I have caught an error thrown when accessing args.concat in my code. It seems weird, and I have removed the shim code before importing polyfill from core-js to avoid conflicts.

You can try to add a debugger point here to check whether args.concat is undefined:

Function.prototype.bind = function () {
    var __method = this, args = $A(arguments), object = args.shift();
    return function () {
+       if (!args.concat) throw new Error('Ooops');
        return __method.apply(object, args.concat($A(arguments)));
    };
};

zloirock · 2022-01-05T10:41:33Z

Please, add a reproducible example. I can't reproduce it just with this code.

aleen42 · 2022-01-06T06:32:27Z

@zloirock Denis, we can reproduce the problem via my commit (aleen42@937d464)

$ npm run test-pollution

> test-pollution
> karma start -f=pollution.js,packages/core-js-bundle/index.js,tests/bundles/tests.js

PhantomJS 2.1.1 (Mac OS 0.0.0) WARN: 'Possible Unhandled Promise Rejection:', TypeError: undefined is not a constructor (evaluating 'args.concat($A(arguments))')
http://localhost:9876/base/pollution.js?8927b7e12418c94e8f945840857d4b03b1afa951:16:46
Error@http://localhost:9876/base/packages/core-js-bundle/index.js?3fbec792f23e50e2ca19b5626f36c32439075414:2854:48
done@http://localhost:9876/base/node_modules/qunit/qunit/qunit.js?c9a269d8ad4db3a08f5a483c41b9bce84062fc4f:2082:26
advanceTestQueue@http://localhost:9876/base/node_modules/qunit/qunit/qunit.js?c9a269d8ad4db3a08f5a483c41b9bce84062fc4f:1985:11
advance@http://localhost:9876/base/node_modules/qunit/qunit/qunit.js?c9a269d8ad4db3a08f5a483c41b9bce84062fc4f:1940:23
unblockAndAdvanceQueue@http://localhost:9876/base/node_modules/qunit/qunit/qunit.js?c9a269d8ad4db3a08f5a483c41b9bce84062fc4f:4321:28
http://localhost:9876/base/node_modules/qunit/qunit/qunit.js?c9a269d8ad4db3a08f5a483c41b9bce84062fc4f:1634:19
PhantomJS 2.1.1 (Mac OS 0.0.0) ERROR

Since Karma has caught the error silently, we can get the detailed error stack by adding try...catch to wrap the whole packages/core-js-bundle/index.js. Here is the detailed stack:

$ npm run test-pollution

> test-pollution
> karma start -f=pollution.js,packages/core-js-bundle/index.js,tests/bundles/tests.js

PhantomJS 2.1.1 (Mac OS 0.0.0) LOG: TypeError: undefined is not a constructor (evaluating 'args.concat($A(arguments))')
http://localhost:9876/base/pollution.js?8927b7e12418c94e8f945840857d4b03b1afa951:16:46
http://localhost:9876/base/packages/core-js-bundle/index.js?24ba48fc928bc58b4ab582da317c09088845b4f6:1174:46
exports@http://localhost:9876/base/packages/core-js-bundle/index.js?24ba48fc928bc58b4ab582da317c09088845b4f6:1100:18
defineProperty@http://localhost:9876/base/packages/core-js-bundle/index.js?24ba48fc928bc58b4ab582da317c09088845b4f6:600:26
http://localhost:9876/base/packages/core-js-bundle/index.js?24ba48fc928bc58b4ab582da317c09088845b4f6:1521:32
exports@http://localhost:9876/base/packages/core-js-bundle/index.js?24ba48fc928bc58b4ab582da317c09088845b4f6:1658:35
exports@http://localhost:9876/base/packages/core-js-bundle/index.js?24ba48fc928bc58b4ab582da317c09088845b4f6:881:13
http://localhost:9876/base/packages/core-js-bundle/index.js?24ba48fc928bc58b4ab582da317c09088845b4f6:3530:2
__webpack_require__@http://localhost:9876/base/packages/core-js-bundle/index.js?24ba48fc928bc58b4ab582da317c09088845b4f6:26:34
http://localhost:9876/base/packages/core-js-bundle/index.js?24ba48fc928bc58b4ab582da317c09088845b4f6:117:20
__webpack_require__@http://localhost:9876/base/packages/core-js-bundle/index.js?24ba48fc928bc58b4ab582da317c09088845b4f6:26:34
http://localhost:9876/base/packages/core-js-bundle/index.js?24ba48fc928bc58b4ab582da317c09088845b4f6:90:37
http://localhost:9876/base/packages/core-js-bundle/index.js?24ba48fc928bc58b4ab582da317c09088845b4f6:91:12
global code@http://localhost:9876/base/packages/core-js-bundle/index.js?24ba48fc928bc58b4ab582da317c09088845b4f6:21483:15
PhantomJS 2.1.1 (Mac OS 0.0.0) WARN: 'Possible Unhandled Promise Rejection:', TypeError: undefined is not a constructor (evaluating 'args.concat($A(arguments))')
http://localhost:9876/base/pollution.js?8927b7e12418c94e8f945840857d4b03b1afa951:16:46
Error@http://localhost:9876/base/packages/core-js-bundle/index.js?24ba48fc928bc58b4ab582da317c09088845b4f6:2854:48
done@http://localhost:9876/base/node_modules/qunit/qunit/qunit.js?c9a269d8ad4db3a08f5a483c41b9bce84062fc4f:2082:26
advanceTestQueue@http://localhost:9876/base/node_modules/qunit/qunit/qunit.js?c9a269d8ad4db3a08f5a483c41b9bce84062fc4f:1985:11
advance@http://localhost:9876/base/node_modules/qunit/qunit/qunit.js?c9a269d8ad4db3a08f5a483c41b9bce84062fc4f:1940:23
unblockAndAdvanceQueue@http://localhost:9876/base/node_modules/qunit/qunit/qunit.js?c9a269d8ad4db3a08f5a483c41b9bce84062fc4f:4321:28
http://localhost:9876/base/node_modules/qunit/qunit/qunit.js?c9a269d8ad4db3a08f5a483c41b9bce84062fc4f:1634:19
PhantomJS 2.1.1 (Mac OS 0.0.0) ERROR

aleen42 · 2022-01-06T06:52:51Z

I think core-js can try to remove all external shims at the start point to avoid such a problem, but it seems not necessary. It is just a suggestion. The main issue is can we avoid removing Array.prototype.concat?

zloirock · 2022-01-06T07:02:25Z

@aleen42 it's not an external shim, since it's an incomplete polyfill that unconditionally replaces the proper feature, it's a case of a broken environment. Need to check, most likely this error happens between Array.prototype.concat removing and adding the proper polyfill. However, I'm not sure that it's something that should be fixed since it's a case of a broken environment.

aleen42 · 2022-01-06T07:09:39Z

A possible direction is to confirm using native methods or shim methods of core-js rather than untrusted ones, during the procedure of removing Array.prototype.concat and replacing back.

zloirock · 2022-01-06T07:13:24Z

Yes, I think I'll do something like that since such .bind was popular some time ago.

aleen42 · 2022-01-06T07:20:46Z

👍🏼

zloirock · 2022-01-06T07:55:37Z

Added a workaround.

Note: Most likely, this check will be removed in core-js@4 with ES3 support.

Thanks for the issue.

aleen42 · 2022-01-06T08:04:21Z

@zloirock is it better to add a testing case for such a polluted environment? But it seems not proper to add polluted code into this repository.

zloirock · 2022-01-06T08:11:02Z

Anyway, we can't detect all possible cases of broken in the userland environment. Now, we have fallbacks for cases with missed .bind, in case of removing ES3 support their removal is implied. Leaving such code will significantly increase the size of minimalistic bundles and it will significantly reduce pluses of removing ES3 support.

aleen42 · 2022-01-06T08:17:57Z

OK, it is just a choice, and feel free to close it. #1035

zloirock · 2022-01-06T08:33:47Z

My previous comment was a continuation of my comment what was before.

@zloirock is it better to add a testing case for such a polluted environment? But it seems not proper to add polluted code into this repository.
#1035

I'm not sure that makes sense - it's a too specific case, I'll think about it, thanks.

aleen42 changed the title ~~Is that Array.prototype.concat will be removed during polyfilll?~~ Is that Array.prototype.concat will be removed during importing polyfilll? Jan 5, 2022

zloirock added the can't reproduce label Jan 5, 2022

zloirock added broken environment and removed can't reproduce labels Jan 6, 2022

zloirock closed this as completed in 1a3c1ca Jan 6, 2022

irbian mentioned this issue Nov 25, 2022

Is worth a noConflict method? #1148

Closed

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Is that `Array.prototype.concat` will be removed during importing polyfilll? #1034

Is that `Array.prototype.concat` will be removed during importing polyfilll? #1034

aleen42 commented Jan 5, 2022 •

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aleen42 commented Jan 5, 2022 •

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aleen42 commented Jan 6, 2022 •

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aleen42 commented Jan 6, 2022

zloirock commented Jan 6, 2022

aleen42 commented Jan 6, 2022

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aleen42 commented Jan 6, 2022

zloirock commented Jan 6, 2022

aleen42 commented Jan 6, 2022 •

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zloirock commented Jan 6, 2022 •

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aleen42 commented Jan 6, 2022

zloirock commented Jan 6, 2022 •

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Is that Array.prototype.concat will be removed during importing polyfilll? #1034

Is that Array.prototype.concat will be removed during importing polyfilll? #1034

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aleen42 commented Jan 5, 2022 • edited

zloirock commented Jan 5, 2022

zloirock commented Jan 5, 2022 • edited

aleen42 commented Jan 5, 2022 • edited

zloirock commented Jan 5, 2022

aleen42 commented Jan 6, 2022 • edited

aleen42 commented Jan 6, 2022

zloirock commented Jan 6, 2022

aleen42 commented Jan 6, 2022

zloirock commented Jan 6, 2022

aleen42 commented Jan 6, 2022

zloirock commented Jan 6, 2022

aleen42 commented Jan 6, 2022 • edited

zloirock commented Jan 6, 2022 • edited

aleen42 commented Jan 6, 2022

zloirock commented Jan 6, 2022 • edited

Is that `Array.prototype.concat` will be removed during importing polyfilll? #1034

Is that `Array.prototype.concat` will be removed during importing polyfilll? #1034

aleen42 commented Jan 5, 2022 •

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zloirock commented Jan 5, 2022 •

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aleen42 commented Jan 5, 2022 •

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aleen42 commented Jan 6, 2022 •

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aleen42 commented Jan 6, 2022 •

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zloirock commented Jan 6, 2022 •

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zloirock commented Jan 6, 2022 •

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