<s>
JScript	B-Language
is	O
Microsoft	O
's	O
legacy	B-Device
dialect	O
of	O
the	O
ECMAScript	B-Language
standard	O
that	O
is	O
used	O
in	O
Microsoft	O
's	O
Internet	B-Application
Explorer	I-Application
11	I-Application
and	O
older	O
.	O
</s>
<s>
JScript	B-Language
is	O
implemented	O
as	O
an	O
Active	B-Application
Scripting	I-Application
engine	O
.	O
</s>
<s>
This	O
means	O
that	O
it	O
can	O
be	O
"	O
plugged	O
in	O
"	O
to	O
OLE	B-Application
Automation	I-Application
applications	O
that	O
support	O
Active	B-Application
Scripting	I-Application
,	O
such	O
as	O
Internet	B-Application
Explorer	I-Application
,	O
Active	B-General_Concept
Server	I-General_Concept
Pages	I-General_Concept
,	O
and	O
Windows	O
Script	O
Host	O
.	O
</s>
<s>
It	O
also	O
means	O
such	O
applications	O
can	O
use	O
multiple	O
Active	B-Application
Scripting	I-Application
languages	O
,	O
e.g.	O
,	O
JScript	B-Language
,	O
VBScript	B-Application
or	O
PerlScript	O
.	O
</s>
<s>
JScript	B-Language
was	O
first	O
supported	O
in	O
the	O
Internet	B-Protocol
Explorer	I-Protocol
3.0	I-Protocol
browser	O
released	O
in	O
August	O
1996	O
.	O
</s>
<s>
Its	O
most	O
recent	O
version	O
is	O
JScript	B-Language
9.0	O
,	O
included	O
in	O
Internet	B-Application
Explorer	I-Application
9	I-Application
.	O
</s>
<s>
JScript	B-Language
10.0	O
is	O
a	O
separate	O
dialect	O
,	O
also	O
known	O
as	O
JScript	B-Language
.NET	I-Language
,	O
which	O
adds	O
several	O
new	O
features	O
from	O
the	O
abandoned	O
fourth	O
edition	O
of	O
the	O
ECMAScript	B-Language
standard	O
.	O
</s>
<s>
It	O
must	O
be	O
compiled	O
for	O
.NET	B-Application
Framework	I-Application
version	O
2	O
or	O
version	O
4	O
,	O
but	O
static	O
type	O
annotations	O
are	O
optional	O
.	O
</s>
<s>
JScript	B-Language
has	O
been	O
criticized	O
for	O
being	O
insecure	O
and	O
having	O
multiple	O
security	O
bugs	O
"	O
exploited	O
by	O
nation-state	O
actors	O
"	O
,	O
leading	O
Microsoft	O
to	O
add	O
an	O
option	O
to	O
disable	O
it	O
.	O
</s>
<s>
As	O
explained	O
by	O
Douglas	O
Crockford	O
in	O
his	O
talk	O
titled	O
The	O
JavaScript	B-Language
Programming	I-Language
Language	I-Language
on	O
YUI	O
Theater	O
,	O
</s>
<s>
However	O
,	O
JScript	B-Language
supports	O
conditional	O
compilation	O
,	O
which	O
allows	O
a	O
programmer	O
to	O
selectively	O
execute	O
code	O
within	O
block	O
comments	O
.	O
</s>
<s>
This	O
is	O
an	O
extension	O
to	O
the	O
ECMAScript	B-Language
standard	O
that	O
is	O
not	O
supported	O
in	O
other	O
JavaScript	B-Language
implementations	O
,	O
thus	O
making	O
the	O
above	O
statement	O
not	O
completely	O
true	O
,	O
although	O
conditional	O
compilation	O
is	O
no	O
longer	O
supported	O
in	O
Internet	B-Application
Explorer	I-Application
11	I-Application
Standards	O
mode	O
.	O
</s>
<s>
Other	O
internal	O
implementation	O
differences	O
between	O
JavaScript	B-Language
and	O
JScript	B-Language
,	O
at	O
some	O
point	O
in	O
time	O
,	O
are	O
noted	O
on	O
the	O
Microsoft	O
Developer	O
Network	O
(	O
MSDN	O
)	O
.	O
</s>
<s>
Although	O
,	O
the	O
default	O
type	O
value	O
for	O
the	O
script	O
element	O
in	O
Internet	B-Application
Explorer	I-Application
is	O
JavaScript	B-Language
,	O
while	O
JScript	B-Language
was	O
its	O
alias	O
.	O
</s>
<s>
In	O
an	O
apparent	O
transition	O
from	O
JScript	B-Language
to	O
JavaScript	B-Language
,	O
online	O
,	O
the	O
Microsoft	B-Application
Edge	I-Application
Developer	O
Guide	O
refers	O
to	O
the	O
Mozilla	O
MDN	O
web	O
reference	O
library	O
as	O
its	O
definitive	O
documentation	O
.	O
</s>
<s>
As	O
of	O
October	O
2017	O
,	O
Microsoft	O
MSDN	O
pages	O
for	O
scripting	O
in	O
Internet	B-Application
Explorer	I-Application
are	O
being	O
redirected	O
there	O
as	O
well	O
.	O
</s>
<s>
This	O
information	O
may	O
not	O
include	O
JScript	B-Language
specific	O
objects	O
,	O
such	O
as	O
Enumerator	O
,	O
which	O
are	O
listed	O
in	O
the	O
JavaScript	B-Language
language	I-Language
reference	O
on	O
Microsoft	O
Docs	O
.	O
</s>
<s>
Those	O
provide	O
additional	O
features	O
that	O
are	O
not	O
included	O
in	O
the	O
ECMA	O
Standards	O
,	O
whether	O
they	O
are	O
supported	O
in	O
the	O
Edge	B-Application
browser	I-Application
or	O
its	O
predecessor	O
.	O
</s>
<s>
The	O
original	O
JScript	B-Language
is	O
an	O
Active	B-Application
Scripting	I-Application
engine	O
.	O
</s>
<s>
Like	O
other	O
Active	B-Application
Scripting	I-Application
languages	O
,	O
it	O
is	O
built	O
on	O
the	O
COM/OLE	B-Application
Automation	I-Application
platform	O
and	O
provides	O
scripting	O
capabilities	O
to	O
host	O
applications	O
.	O
</s>
<s>
This	O
is	O
the	O
version	O
used	O
when	O
hosting	O
JScript	B-Language
inside	O
a	O
Web	O
page	O
displayed	O
by	O
Internet	B-Application
Explorer	I-Application
,	O
in	O
an	O
HTML	B-Application
application	I-Application
before	O
IE9	B-Application
,	O
as	O
well	O
as	O
in	O
classic	B-General_Concept
ASP	I-General_Concept
,	O
Windows	O
Script	O
Host	O
scripts	O
and	O
other	O
Automation	B-Application
environments	O
.	O
</s>
<s>
JScript	B-Language
is	O
sometimes	O
referred	O
to	O
as	O
"	O
classic	O
JScript	B-Language
"	O
or	O
"	O
Active	B-Application
Scripting	I-Application
JScript	B-Language
"	O
to	O
differentiate	O
it	O
from	O
newer	O
.NET-based	O
versions	O
.	O
</s>
<s>
Some	O
versions	O
of	O
JScript	B-Language
are	O
available	O
for	O
multiple	O
versions	O
of	O
Internet	B-Application
Explorer	I-Application
and	O
Windows	O
.	O
</s>
<s>
For	O
example	O
,	O
JScript	B-Language
5.7	O
was	O
introduced	O
with	O
Internet	B-Application
Explorer	I-Application
7.0	I-Application
and	O
is	O
also	O
installed	O
for	O
Internet	B-Application
Explorer	I-Application
6.0	I-Application
with	O
Windows	B-Application
XP	I-Application
Service	O
Pack	O
3	O
,	O
while	O
JScript	B-Language
5.8	O
was	O
introduced	O
with	O
Internet	B-Application
Explorer	I-Application
8.0	I-Application
and	O
is	O
also	O
installed	O
with	O
Internet	B-Application
Explorer	I-Application
6.0	I-Application
on	O
Windows	O
Mobile	O
6.5	O
.	O
</s>
<s>
Microsoft	O
's	O
implementation	O
of	O
ECMAScript	B-Language
5th	O
Edition	O
in	O
Windows	O
8	O
Consumer	O
Preview	O
is	O
called	O
JavaScript	B-Language
and	O
the	O
corresponding	O
Visual	B-Application
Studio	I-Application
11	I-Application
Express	O
Beta	O
includes	O
a	O
"	O
completely	O
new	O
"	O
,	O
full-featured	O
JavaScript	B-Language
editor	O
with	O
IntelliSense	B-Application
enhancements	O
for	O
HTML5	B-Application
and	O
ECMAScript	B-Language
5	O
syntax	O
,	O
"	O
VSDOC	O
"	O
annotations	O
for	O
multiple	O
overloads	O
,	O
simplified	O
DOM	B-General_Concept
configuration	O
,	O
brace	O
matching	O
,	O
collapsible	O
outlining	O
and	O
"	O
go	O
to	O
definition	O
"	O
.	O
</s>
<s>
JScript	B-Language
is	O
also	O
available	O
on	O
Windows	B-Operating_System
CE	I-Operating_System
(	O
included	O
in	O
Windows	O
Mobile	O
,	O
optional	O
in	O
Windows	B-Operating_System
Embedded	I-Operating_System
CE	I-Operating_System
)	O
.	O
</s>
<s>
The	O
Windows	B-Operating_System
CE	I-Operating_System
version	O
lacks	O
Active	O
Debugging	O
.	O
</s>
<s>
Managed	O
JScript	B-Language
is	O
an	O
implementation	O
of	O
JScript	B-Language
for	O
the	O
Dynamic	B-Application
Language	I-Application
Runtime	I-Application
,	O
it	O
is	O
part	O
of	O
Microsoft	O
's	O
dynamic	O
languages	O
for	O
.NET	B-Application
along	O
with	O
IronRuby	B-Language
,	O
IronPython	B-Application
,	O
and	O
Dynamic	B-Language
Visual	I-Language
Basic	I-Language
.	O
</s>
<s>
Unlike	O
JScript	B-Language
.NET	I-Language
,	O
which	O
is	O
less	O
dynamic	O
than	O
the	O
original	O
JScript	B-Language
but	O
provides	O
CLS	O
compatibility	O
,	O
Managed	O
JScript	B-Language
is	O
designed	O
on	O
top	O
of	O
the	O
DLR	B-Application
and	O
provides	O
the	O
features	O
needed	O
for	O
scripting	O
scenarios	O
.	O
</s>
<s>
While	O
it	O
is	O
primarily	O
designed	O
to	O
be	O
used	O
within	O
Silverlight	B-Application
and	O
ASP.NET	B-Application
at	O
this	O
time	O
,	O
it	O
can	O
also	O
easily	O
be	O
embedded	O
within	O
any	O
.NET	B-Application
application	O
.	O
</s>
<s>
Managed	O
JScript	B-Language
is	O
not	O
supported	O
in	O
the	O
.NET	B-Operating_System
Compact	I-Operating_System
Framework	I-Operating_System
.	O
</s>
<s>
JScript	B-Language
"	O
Chakra	B-Language
"	O
is	O
based	O
on	O
the	O
JScript	B-Language
(	O
COM	O
classic	O
)	O
version	O
,	O
but	O
it	O
has	O
been	O
redesigned	O
to	O
improve	O
performance	O
in	O
Internet	B-Application
Explorer	I-Application
9	I-Application
at	O
the	O
expense	O
of	O
proper	O
Active	B-Application
Scripting	I-Application
engine	O
compatibility	O
.	O
</s>
<s>
It	O
requires	O
a	O
specific	O
Microsoft	O
JavaScript	B-Language
Hosting	O
(	O
JsRT	O
)	O
API	O
for	O
proper	O
use	O
.	O
</s>
<s>
Therefore	O
,	O
it	O
is	O
installed	O
side	O
by	O
side	O
with	O
JScript	B-Language
5.x	O
and	O
is	O
only	O
used	O
by	O
Internet	B-Application
Explorer	I-Application
9	I-Application
and	O
later	O
as	O
well	O
as	O
JsRT	O
hosts	O
,	O
while	O
other	O
Active	B-Application
Scripting	I-Application
hosts	O
keep	O
using	O
the	O
5.x	O
version	O
when	O
requesting	O
the	O
JScript	B-Language
engine	O
.	O
</s>
<s>
There	O
are	O
two	O
versions	O
of	O
the	O
Chakra	B-Language
engine	O
,	O
the	O
original	O
one	O
used	O
by	O
Internet	B-Application
Explorer	I-Application
9	I-Application
and	O
later	O
,	O
and	O
sometimes	O
referred	O
to	O
as	O
"	O
jscript9.dll	O
"	O
or	O
"	O
legacy	B-Device
Chakra	B-Language
engine	O
"	O
,	O
and	O
a	O
second	O
one	O
used	O
by	O
Microsoft	B-Application
Edge	I-Application
browser	O
and	O
sometimes	O
referred	O
to	O
as	O
"	O
new	O
Chakra	B-Language
engine	O
"	O
,	O
"	O
Edge	B-Application
engine	O
"	O
or	O
"	O
Chakra.dll	O
"	O
.	O
</s>
<s>
Both	O
Chakra	B-Language
versions	O
can	O
be	O
used	O
by	O
other	O
applications	O
using	O
the	O
JsRT	O
API	O
and	O
can	O
be	O
installed	O
side	O
by	O
side	O
.	O
</s>
<s>
See	O
separate	O
page	O
about	O
new	O
Chakra	B-Language
(	O
Edge	B-Application
)	O
engine	O
.	O
</s>
<s>
JScript	B-Language
.NET	I-Language
is	O
a	O
Microsoft	O
.NET	B-Application
implementation	O
of	O
JScript	B-Language
.	O
</s>
<s>
It	O
is	O
a	O
CLI	O
language	O
and	O
thus	O
inherits	O
very	O
powerful	O
features	O
,	O
but	O
lacks	O
many	O
features	O
of	O
the	O
original	O
JScript	B-Language
language	O
,	O
making	O
it	O
inappropriate	O
for	O
many	O
scripting	O
scenarios	O
.	O
</s>
<s>
JScript	B-Language
.NET	I-Language
can	O
be	O
used	O
for	O
ASP.NET	B-Application
pages	O
and	O
for	O
complete	O
.NET	B-Application
applications	O
,	O
but	O
the	O
lack	O
of	O
support	O
for	O
this	O
language	O
in	O
Microsoft	B-Application
Visual	I-Application
Studio	I-Application
places	O
it	O
more	O
as	O
an	O
upgrade	O
path	O
for	O
classic	B-General_Concept
ASP	I-General_Concept
using	O
classic	O
JScript	B-Language
than	O
as	O
a	O
new	O
first-class	O
language	O
.	O
</s>
<s>
JScript	B-Language
.NET	I-Language
is	O
not	O
supported	O
in	O
the	O
.NET	B-Operating_System
Compact	I-Operating_System
Framework	I-Operating_System
.	O
</s>
<s>
Note	O
:	O
JScript	B-Language
.NET	I-Language
versions	O
are	O
not	O
related	O
to	O
classic	O
JScript	B-Language
versions	O
.	O
</s>
<s>
JScript	B-Language
.NET	I-Language
is	O
a	O
separate	O
product	O
.	O
</s>
<s>
Even	O
though	O
JScript	B-Language
.NET	I-Language
is	O
not	O
supported	O
within	O
the	O
Visual	B-Application
Studio	I-Application
IDE	O
,	O
its	O
versions	O
are	O
in	O
sync	O
with	O
other	O
.NET	B-Application
languages	O
versions	O
(	O
C#	B-Application
,	O
VB.NET	B-Language
,	O
VC++	B-Application
)	O
that	O
follow	O
their	O
corresponding	O
Visual	B-Application
Studio	I-Application
versions	O
.	O
</s>
<s>
.NET	B-Application
Framework	I-Application
3.0	O
and	O
3.5	O
are	O
built	O
on	O
top	O
of	O
2.0	O
and	O
do	O
not	O
include	O
the	O
newer	O
JScript.NET	B-Language
release	O
(	O
version	O
10.0	O
for	O
.NET	B-Application
Framework	I-Application
4.0	O
)	O
.	O
</s>
