"isPlainObject" losts compatibility against 1.9.1

[ystk_skm (brilliantpenguin@…]

You are modifying "isPlainObject" method and it is now losts compatibility against 1.9.1.
When some prototype is set via Object, the prototype have "isPrototypeOf" method. Please check an example for the matter:

​http://localhost/cloudplus.me/EasyCoding/

# my checking conditon:

Google Chrome 25.0.1364.152 (Official Build 185281)
OS Mac OS X
WebKit 537.22 (@144108)
JavaScript V8 3.15.11.16

[ystk_skm (brilliantpenguin@…]

I'm sorry for my mistake. The correct url is: ​http://cloudplus.me/EasyCoding/

[ajpiano]

#13572 is a duplicate of this ticket.

[Rick Waldron]

Confirm that this is a "regression", but jQuery 1.9.x was wrong.

The constructed object _IS_ a plain object, because the code is paving over the constructor's prototype:

function C() {}
C.prototype = {};
c = new C();
console.log(c.constructor);
// > function Object() { [native code] }

If the program resets the constructor, the expected results:

function C() {}
C.prototype = {
  constructor: C
};
c = new C();
console.log(c.constructor);
// > function C() {}

In jQuery.isPlainObject's case, the OPs example code only works in jQuery 1.9.x because it has properties on the object that was used as the prototype, which is what jQuery 1.9.x used to determine property ownership and therefore detect possible inheritance chains.

Everything works the way you want it to until you try to test this:

var c, extended;
function C() {}
C.prototype = {};
c = new C();

extended = jQuery.extend( true, {}, {
  target: c
});

strictEqual( extended.target, c, "Deep extended objects retain identity" );

... Without any properties on that prototype, the jQuery 1.9 way will fail as well: ​http://jsfiddle.net/rwaldron/7Jg8Q/

Unfortunately, the regression stands and I'll have to restore the behaviour, but it will still be broken (ie. it's correct, but the expectations of the calling code is wrong).

[Rick Waldron]

Fixes #13571. jQuery.isPlainObject 1.9.x compatibility

Signed-off-by: Rick Waldron <waldron.rick@…>

Changeset: 8d1c42296fefc4e79189b6c2d78a8a78fdd9576d

[Rick Waldron]

We've decided that this breaking change will remain in 2.x, but will be accompanied by documentation explaining the issue encountered here.

Reverted: ​https://github.com/jquery/jquery/commit/5c82d36f194a854a19f81bebd3ed1a6e7559c811

[ystk_skm <brilliantpenguin@…>]

rwaldron

I can accept your decision easily.

[Rick Waldron]

wow, thanks for being so reasonable :) that's refreshing... you just made my night

[ystk_skm <brilliantpenguin@…>]

I know that less code is fast code. Thanks for your good decision.
Take care for the same kind of claim for "isPlainObject" not to change again (and you try to revert again).

[Rick Waldron]

@timmywil, why is this reopened? (I'm just curious)

[Timmy Willison]

@rwaldron: Wait, I'm confused now. You reopened it. I just put it back to assigned.

[Rick Waldron]

Yep, you're right. Oops!

[Rick Waldron]

#13715 is a duplicate of this ticket.

[m_gol]

Why the check:

!core_hasOwn.call(obj, "constructor")

is needed in jQuery 1.x anyway? All unit tests are passed by oldIE when this line is missing.

If it's really needed, a unit test for that should be written.

[Rick Waldron]

#14227 is a duplicate of this ticket.