v3.6.0-beta.3 JQuery.extend (recursively) is broken

[pieter-v]

We use some jquery plugins (e.g.: bootstrap-daterangepicker), which uses the extend method from jquery. In v3.6.0-beta.3, this fails as jquery recursively iterates through the [] property of an array (we use the array prototype extensions of Ember)

ember-source@3.5.1
$.extend(true, {}, {a:['a']}) gives

{a: Array(1)}

ember-source@3.6.0-beta.3
$.extend(true, {}, {a:['a']}) gives

jquery.js:282 Uncaught RangeError: Maximum call stack size exceeded
    at Function.jQuery.extend.jQuery.fn.extend (jquery.js:282)
    at Function.jQuery.extend.jQuery.fn.extend (jquery.js:282)
    at Function.jQuery.extend.jQuery.fn.extend (jquery.js:282)
    at Function.jQuery.extend.jQuery.fn.extend (jquery.js:282)
    at Function.jQuery.extend.jQuery.fn.extend (jquery.js:282)
    at Function.jQuery.extend.jQuery.fn.extend (jquery.js:282)
    at Function.jQuery.extend.jQuery.fn.extend (jquery.js:282)
    at Function.jQuery.extend.jQuery.fn.extend (jquery.js:282)
    at Function.jQuery.extend.jQuery.fn.extend (jquery.js:282)
    at Function.jQuery.extend.jQuery.fn.extend (jquery.js:282)

[rwjblue]

This is using the same version of jQuery between the two?

I’m not immediately aware of a change that would have caused this. We will probably need to bisect to track it down...

[pieter-v]

To reproduce, I created a new project (so no extra dependencies)

ember new extend --yarn

This installs ember@3.5.1
I run the default application and in the browser console I executed the command

$.extend(true, {}, {a:['a']})

Then I upgraded ember

yarn upgrade ember-source@3.6.0-beta.3

And this gives the error

[pieter-v]

JQuery uses for ( name in options ) construct to iterate over the properties.

In ember 3.5.1

Object.getOwnPropertyDescriptor([].__proto__, '[]')

returns

{get: ƒ, set: undefined, enumerable: false, configurable: true}

and in ember 3.6.0-beta.3
the result is

{get: ƒ, set: undefined, enumerable: true, configurable: true}

As a for...in construct iterates over all enumerable properties, in ember 3.5.1 the [] is not included, but it is included in ember 3.6.0-beta.3

[lougreenwood]

I'm seeing a very similar issue with ember-inputmask:

[Error] RangeError: Maximum call stack size exceeded.
	get (vendor.js:28394)
	extend (vendor.js:99178)
	extend (vendor.js:99190)
	extend (vendor.js:99190)
	extend (vendor.js:99190)
	extend (vendor.js:99190)
	....
	extend (vendor.js:99190)

Stacktrace shows it's this line of code code which triggers it - which is also a .extend() like the jQuery problem above: https://github.com/RobinHerbots/Inputmask/blob/5.x/lib/dependencyLibs/inputmask.dependencyLib.js#L317

I've tried all beta versions (1-4) and the problem exists in all versions.

[pieter-v]

As a workaround I execute the following code in an initializer

        // TODO: remove once https://github.com/emberjs/ember.js/issues/17190 has been fixed
        const properties = ['[]', 'firstObject', 'lastObject', 'hasArrayObservers', '@each'];
        properties.forEach(property => {
            const desc = Object.getOwnPropertyDescriptor([].__proto__, property);
            desc.enumerable = false;
            Object.defineProperty([].__proto__, property, desc);
        });

[rwjblue]

This seems like a regression of the fixes in #16169 which was specifically trying to address this issue...

[jacobq]

I can confirm that this problem still happens in 3.6 and 3.7.0-beta.1.
One easy way to check for regression is to run for (var x in []) console.log(x):

• In vanilla JS: logs nothing
• In Ember 3.5.1 logs _super
• In Ember 3.6.0 & 3.7.0-beta.1 it logs _super, [], firstObject, lastObject hasArrayObservers, and @each

See also ember-cli/ember-cli#8295

Update: I created a PR to incorporate a test for this, though it doesn't actually fix the problem.

[jacobq]

This is using the same version of jQuery between the two?

I’m not immediately aware of a change that would have caused this. We will probably need to bisect to track it down...

Running git bisect with the test I wrote in #17374 suggests that the problem was introduced by 02af025 246435e

[rwjblue]

Hmm, that seems somewhat surprising because I think that landed after this issue was reported right?

[jacobq]

OK, I am trying again but using more automation (was running the test myself before and may have made a mistake).

Create executable test.sh script with the following contents:

rm -rf dist/ node_modules/
yarn
ember build
node -e "require('./dist/ember.debug.js'); const a = []; for (let p in a) { if (a[p] === a) { throw new Error(\`a[\"\${p}\"] === a\`)}}"

Then bisect like this

git checkout master
git bisect start
git bad
git bisect good v3.5.1
git bisect run ./test.sh

When I ran this just now it finished with:

246435e7260f45d9e5cc35a4a8b4de4f011f3625 is the first bad commit
commit 246435e7260f45d9e5cc35a4a8b4de4f011f3625
Author: bekzod <bekzod@me.com>
Date:   Mon Jun 11 21:42:16 2018 +0500

    avoid double define for native descriptors

:040000 040000 173ea3396625a0bf0d5ddb72c7591daa93151e33 a4a4903a3f9c3ef40ba3ac9699056005d1b2046c M	packages
bisect run success

[rwjblue]

Awesome, that makes sense!

[jacobq]

Now someone just needs to fix it :D

[rwjblue]

Fixed by #17374