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[bug] new Function string tag is "global" and prototype methods like .bind() are missing. #19651
Description
I've got a weird issue. First, notice the weird output in the following screenshot, where temp1 is a function created with new Function(...):
The string tag appears to be "global" (hence [object global] output) and .bind() is missing!
To reproduce, check out the following repo on the following branch: https://github.com/trusktr/lowclass/tree/nodejs-issue-19651
After cloning and checking out the branch, just run node test.js (there's no dependencies to install) which will result in the output:
> node test.js
es5 mode
es5 mode
about to call super constructor in Dog
WTF? [object global] function false
/home/trusktr/Downloads/src/trusktr+lowclass/src/index.js:387
descriptor.value = descriptor.value.bind( instance )
^
TypeError: descriptor.value.bind is not a function
at copyDescriptors (/home/trusktr/Downloads/src/trusktr+lowclass/src/index.js:387:53)
at copyDescriptors (/home/trusktr/Downloads/src/trusktr+lowclass/src/index.js:352:18)
at getSuperHelperObject (/home/trusktr/Downloads/src/trusktr+lowclass/src/index.js:383:9)
at superHelper (/home/trusktr/Downloads/src/trusktr+lowclass/src/index.js:368:16)
at Dog.constructor (/home/trusktr/Downloads/src/trusktr+lowclass/test.js:28:13)
at new Dog (eval at Class (/home/trusktr/Downloads/src/trusktr+lowclass/src/index.js:135:20), <anonymous>:30:54)
at Object.<anonymous> (/home/trusktr/Downloads/src/trusktr+lowclass/test.js:35:15)
at Module._compile (module.js:649:30)
at Object.Module._extensions..js (module.js:660:10)
at Module.load (module.js:561:32)
If you look at line 10 of test.js, and make uncomment line 10 and comment the next lines so it look like the following then the error goes away:
const Clazz = Class
//const Clazz = Class.configure({
//mode: 'es5',
////mode: 'Reflect.construct',
//})So the error is somehow related to the Class.configure call, but I haven't found why though.
As far as I know, I'm not messing with Function.prototype, so I don't see how .bind() could possibly be missing from the function that I am creating. Have I missed something obvious, or is this a bug?
Activity
targos commentedon Mar 28, 2018
It's because of this line: https://github.com/trusktr/lowclass/blob/3854ad9d5f9178afa97c59de08d0909591fa1de0/src/index.js#L176
ParentClassis the global object, so theAnimalconstructor, while being a function, will loseFunction.prototypemethods there and inherittoStringfromObject.prototypeTimothyGu commentedon Mar 28, 2018
Quick analysis:
_Class.configurereturns a function defined byThis returned function is stored in
Clazz.test.jsthen calls that function in the global scope (const Animal = Clazz(...)), sothisis set toglobalwhenClazzis called. This is then reflected in theClassfunction defined inindex.jswhich hasconst ParentClass = this || Object, wherethisisglobal.On the other hand, when
const Clazz = Class,Classrefers to the_Classfunction inindex.js, and there isn't theClass.call(this)in that function. So theClassisundefinedwhen it is called by_Class.Next time, please make sure file this type of issues at nodejs/help when it's not clear that there is a bug in Node.js.
trusktr commentedon Mar 29, 2018
Will do. Sorry about that. I see it now, I forgot a "use strict" in there. Many thanks!
trusktr commentedon Mar 29, 2018
I forgot a "use strict" in there.