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From: Asen Bozhilov <asen.bozhilov@gmail.com>
Newsgroups: comp.lang.javascript
Subject: Re: call by reference
Date: Tue, 27 Mar 2012 05:15:35 -0700 (PDT)
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Evertjan:

> JavaScript DOES support call-by-reference.
>=20
> All objects are called by reference:

This is long discussed topic. Your terminology even and it is not correct s=
eems more closer to the point. JavaScript uses the evaluation strategy call=
ed "Call by sharing".=20
<URL: http://en.wikipedia.org/wiki/Evaluation_strategy#Call_by_sharing>=20

It is often mistaken with  "Call by reference", but it slightly differ:=20

"The semantics of call-by-sharing differ from call-by-reference in that ass=
ignments to function arguments within the function aren't visible to the ca=
ller (unlike by-reference semantics)[citation needed], so e.g. if a variabl=
e was passed, it is not possible to simulate an assignment on that variable=
 in the caller's scope. However since the function has access to the same o=
bject as the caller (no copy is made), mutations to those objects, if the o=
bjects are mutable, within the function are visible to the caller, which ma=
y appear to differ from call-by-value semantics."  =20

=20
> <script type=3D'text/javascript'>
>=20
> var myObj =3D {};
>=20
> myObj.myValue =3D 7;
> alert(myObj.myValue); // 7
>=20
> function f(a) {
>   a.myValue =3D 33;
> };
>=20
> f(myObj);
> alert(myObj.myValue); // 33
>=20
> </script>

It does not prove your point.=20

function f(o) {
    o.foo =3D 10;
    o =3D {foo : 0};
}

var obj =3D {foo : 5};
f(obj);

print(obj.foo); //10

This example shows that JavaScript does not use "Call by reference" if it u=
sed the value of `foo` would be 0 instead. The example shows "Call by shari=
ng" strategy.=20