Suggest adding non-enumerable properties support when implementing Object.assign under IE8

[aleen42]

Under IE8, there are some non-enumerable properties like toString, which is actually not standard. However, the shim for Object.assign has not solved the problem for us, like what described here, and I hope the source shim can do this for us.

[aleen42]

The solved code snippet is shown as followed:

let fn = Object.assign;
Object.assign = function () {
    const [target, ...sources] = [].slice.call(arguments, 0);
    const result = fn.apply(this, [target, ...sources]);

    [
        'valueOf',
        'isPrototypeOf',
        'toString',
        'hasOwnProperty',
        'toLocaleString',
        'propertyIsEnumerable',
    ].forEach(property => {
        if (property === 'propertyIsEnumerable'
            || !({[property] : null}).propertyIsEnumerable(property)) {
            /** non-enumerable properties */
            sources.forEach(source => source
                                      && source.hasOwnProperty(property)
                                      && (result[property] = source[property]));
        }
    });

    return result;
};

[zloirock]

A workaround like this should be already used in enumerable keys related core-js features.

[aleen42]

Has that feature been already released?

[zloirock]

Yes. I'll test it a little later.

[aleen42]

Thanks for your responses.

[zloirock]

Looks like a bug. Object.keys works with those keys fine, but Object.assign not. But they should use the same way of getting enumerable keys internally.

[zloirock]

Seems the problem in one propertyIsEnumerable extra check.

[aleen42]

Check it and wait for upgrading.

[aleen42]

@zloirock, The problem is still existed with using @3.1.2.

A simple case described here can be used as a test case.

[zloirock]

@aleen42 your test case passed in 3.1.2, but I can confirm that 2.6.8 still has this problem.

[zloirock]

Nope, 2.6.8 also works fine, some problems with the cache in the testing platform.

[aleen42]

With using 2.6.8:

[aleen42]

Are you sure you have run your test under IE8?

[zloirock]

@aleen42

[aleen42]

wired, the case I tested was where I only required the core-js/shim file rather than the client/shim under 2.6.8. It seemed client/shim was OK for me.

It is my fault where I have a sub dependencie which depends on another low version.