Closed Bug 1251909 Opened 8 years ago Closed 8 years ago

`this` value in Array.prototype.concat should be converted to object

Categories

(Core :: JavaScript: Standard Library, defect)

Product:
Core
Component:
JavaScript: Standard Library
Type:
defect
Priority:
Not set
Severity:
normal

Tracking

()

Status:
RESOLVED FIXED

People

(Reporter: maxdamantus, Unassigned)

References

Details

User Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2272.89 Safari/537.36

Steps to reproduce:

Evaluate the expression `typeof Array.prototype.concat.call(4)[0]`.


Actual results:

The expression evaluated to the string "number".


Expected results:

The expression should evaluate to "object"; ECMA262 v3, v5 and v6 describe the `this` value as unconditionally being passed through `ToObject` before being used to initialise the array of prospect arrays.
bug 1233642 (rewrites whole Array.prototype.concat implementation) will fix this.
it may take some more time to fix the performance issue there tho.
Status: UNCONFIRMED → NEW
Ever confirmed: true
See Also: → 1233642
Marking as resolved since it seems like bug 1233642 fixes this issue. Works as expected on FF49 and Nightly.
Status: NEW → RESOLVED
Closed: 8 years ago
Resolution: --- → FIXED
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