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Issue 709597 link

Starred by 2 users
Status: WontFix
Owner:
adamk@chromium.org
Closed: Apr 2017
Cc:
█ krajshree@chromium.org
gsat...@chromium.org
adamk@chromium.org
Components:
EstimatedDays: ----
NextAction: ----
OS: Linux
Pri: 2
Type: Bug



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ReferenceError on setting paramater to default parameter of same name

Reported by rschako...@gmail.com, Apr 7 2017 
UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/57.0.2987.133 Safari/537.36

Steps to reproduce the problem:
1. Declare function with identical param and default param name
2. Call function

What is the expected behavior?
Works as expected in Firefox.

What went wrong?
Throws that the identifier is undefined, even if previously declared and/or set explicitly.

Applies to functions, arrow functions, and class/object methods.

Did this work before? N/A 

Chrome version: 57.0.2987.133  Channel: stable
OS Version: 16.04
Flash Version: 

var pos = 10

foo = (p = pos) => p      // OK
bar = (pos = pos) => pos  // ReferenceError

console.log(foo())
console.log(bar())

Comment 1 by rschako...@gmail.com, Apr 7 2017 

I've just realized that the behavior is 'different' in Firefox but not at all 'as expected'.

I had only tried 'var pos' in FF, not 'var pos = 10'. Firefox does not throw, but rather the value silently becomes undefined in the function scope, and remains as-is outside the scope.

Comment 2 by tkent@chromium.org, Apr 10 2017

Components: -Blink Blink>JavaScript

Comment 3 by krajshree@chromium.org, Apr 12 2017

Cc: krajshree@chromium.org
Labels: Needs-Feedback
rschakotay@ - Thanks for filing the issue...!!

Could you please provide a sample html file, expected and actual behavior to test this issue from TE-end.

This will help us in triaging the issue further.

Thanks...!!

Comment 4 by hablich@chromium.org, Apr 12 2017

Components: -Blink>JavaScript Blink>JavaScript>Language
Owner: adamk@chromium.org
Status: Assigned (was: Unconfirmed)
in Chrome 58 both of them throw the error. I suppose this is expected?

Comment 5 by adamk@chromium.org, Apr 12 2017

Status: WontFix (was: Assigned)
This is working as intended. The "pos = pos" case fails because the "pos" on the right-hand side refers to the "pos" parameter name, but reading from it fails, because it's not yet been initialized.
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