Assigning a value to Array.prototype[1] will result in an error ：node:internal/process/task_queues:77 callback();

[LoongZP]

Version

v20.14.0

Platform

Microsoft Windows NT 10.0.22631.0
x64

Subsystem

No response

What steps will reproduce the bug?

code:
Array.prototype[1] = 2
console.log(Array.prototype);

result:

How often does it reproduce? Is there a required condition?

When I knew that Array.prototype was an Array, I tried to assign a value to Array.prototype[x].
Assigning only Array.prototype[1] results in an error that will occur when reading Array.prototype.

What is the expected behavior? Why is that the expected behavior?

In Chrome, you will get the following results：

Array.prototype[1] = 2
console.log(Array.prototype);

result:
[1: 2, at: ƒ, concat: ƒ, copyWithin: ƒ, fill: ƒ, find: ƒ, …]

What do you see instead?

code:
Array.prototype[1] = 2
console.log(Array.prototype);

result:
Object(2) [ <1 empty item>, 2 ]
node:internal/process/task_queues:77
callback();
^
TypeError: callback is not a function
at process.processTicksAndRejections (node:internal/process/task_queues:77:11)

Node.js v20.14.0

Additional information

No response

[avivkeller]

I'm unable to reproduce in v22.6.0, but I haven't tested in v20. @LoongZP can you reproduce in the latest version of v20? (v20.16.0)

➜  ~ node
Welcome to Node.js v22.6.0.
Type ".help" for more information.
> Array.prototype[1] = 2
2
> console.log(Array.prototype);
Object(2) [ <1 empty item>, 2 ]
undefined
>

[LoongZP]

@redyetidev
The strange thing is that I also have no error when executing in interactive mode in node, it only occurs when node xx.js, which I also found in v22.3.0.

[avivkeller]

I'll retest later, but for now could you try to reproduce in the latest version of those release lines?

v22.6.0
v20.16.0

[LoongZP]

@redyetidev
I also tried it in ubuntu (node v20.11.1.) and found this issue as well.

[LoongZP]

@redyetidev
I've tried the following:

	os	node  version	result
my coputer	Microsoft Windows NT 10.0.22631.0   x64	22.6.0	x
my coputer	Microsoft Windows NT 10.0.22631.0   x64	22.3.0	x
my coputer	Microsoft Windows NT 10.0.22631.0   x64	20.14.0	x
other's coputer	Linux version 5.15.0-118-generic (buildd@lcy02-amd64-103) (gcc (Ubuntu 9.4.0-1ubuntu120.04.2) 9.4.0, GNU ld (GNU Binutils for Ubuntu) 2.34) #12820.04.1-Ubuntu SMP Wed Jul 17 13:41:17 UTC 2024	20.11.1	x
other's coputer	Microsoft Windows NT 10.0.22631.0   x64	20.9.9	x

NOTE:
It's strange that there is no problem with assigning a value to Array.prototype[0/2/3/4...].

[avivkeller]

Array.prototype[1] = 2;
console.log(Array.prototype);

$ node repro.js
Object(2) [ <1 empty item>, 2 ]
node:internal/process/task_queues:77
          callback();
          ^

TypeError: callback is not a function
    at process.processTicksAndRejections (node:internal/process/task_queues:77:11)

Node.js v22.6.0

---

Array.prototype[0] = 2;
console.log(Array.prototype);

$ node repro.js
Object(1) [ 2 ]

[LoongZP]

@redyetidev
So what is the reason, it's a very strange mistake.

[moorthid2023]

I think leaving first index cause the issue

Array.prototype[0]=2;
let problem = Array.prototype;
console.log(problem);

C:\Users\Moorthi\De
Object(1) [ 2 ]

[LoongZP]

I think leaving first index cause the issue

Array.prototype[0]=2; let problem = Array.prototype; console.log(problem);

C:\Users\Moorthi\De Object(1) [ 2 ]

No, you can try the code below:

Array.prototype[2] = 2;
let problem = Array.prototype;
console.log(problem);

[avivkeller]

Array.prototype[2] = 2;
let problem = Array.prototype;
console.log(problem);

The failing line is:

node/lib/internal/process/task_queues.js

Line 85 in 8b0c699

callback();

So something is calling that line incorrectly when Array.prototype[1] isn't what it should be...

I've added the console label, as this isn't reproducible without calling console.log.

---

The following prefixes each behave differently:

// Crashes
Array.prototype[1] = 1;

// Hangs
Array.prototype[1] = null;

// Works normally
Array.prototype[1] = undefined;

The error can be reproduced without console (but this function is called from the console.log call):

process.nextTick(()=>{});

[avivkeller]

@nodejs/process