<s>
CoffeeScript	B-Application
is	O
a	O
programming	O
language	O
that	O
compiles	O
to	O
JavaScript	B-Language
.	O
</s>
<s>
It	O
adds	O
syntactic	O
sugar	O
inspired	O
by	O
Ruby	B-Language
,	O
Python	B-Language
,	O
and	O
Haskell	B-Language
in	O
an	O
effort	O
to	O
enhance	O
JavaScript	B-Language
's	O
brevity	O
and	O
readability	O
.	O
</s>
<s>
Specific	O
additional	O
features	O
include	O
list	B-Language
comprehension	I-Language
and	O
destructuring	O
assignment	O
.	O
</s>
<s>
CoffeeScript	B-Application
support	O
is	O
included	O
in	O
Ruby	B-Application
on	I-Application
Rails	I-Application
version	O
3.1	O
and	O
Play	B-Language
Framework	I-Language
.	O
</s>
<s>
In	O
2011	O
,	O
Brendan	O
Eich	O
referenced	O
CoffeeScript	B-Application
as	O
an	O
influence	O
on	O
his	O
thoughts	O
about	O
the	O
future	O
of	O
JavaScript	B-Language
.	O
</s>
<s>
On	O
December	O
13	O
,	O
2009	O
,	O
Jeremy	O
Ashkenas	O
made	O
the	O
first	O
Git	B-Application
commit	O
of	O
CoffeeScript	B-Application
with	O
the	O
comment	O
:	O
"	O
initial	O
commit	O
of	O
the	O
mystery	O
language.	O
"	O
</s>
<s>
The	O
compiler	O
was	O
written	O
in	O
Ruby	B-Language
.	O
</s>
<s>
On	O
February	O
21	O
,	O
2010	O
,	O
he	O
committed	O
version	O
0.5	O
,	O
which	O
replaced	O
the	O
Ruby	B-Language
compiler	O
with	O
a	O
self-hosting	O
version	O
in	O
pure	O
CoffeeScript	B-Application
.	O
</s>
<s>
By	O
that	O
time	O
the	O
project	O
had	O
attracted	O
several	O
other	O
contributors	O
on	O
GitHub	B-Application
,	O
and	O
was	O
receiving	O
over	O
300	O
page	O
hits	O
per	O
day	O
.	O
</s>
<s>
On	O
December	O
24	O
,	O
2010	O
,	O
Ashkenas	O
announced	O
the	O
release	O
of	O
stable	O
1.0.0	O
to	O
Hacker	B-Application
News	I-Application
,	O
the	O
site	O
where	O
the	O
project	O
was	O
announced	O
for	O
the	O
first	O
time	O
.	O
</s>
<s>
On	O
September	O
18	O
,	O
2017	O
,	O
version	O
2.0.0	O
was	O
introduced	O
,	O
which	O
"	O
aims	O
to	O
bring	O
CoffeeScript	B-Application
into	O
the	O
modern	O
JavaScript	B-Language
era	O
,	O
closing	O
gaps	O
in	O
compatibility	O
with	O
JavaScript	B-Language
while	O
preserving	O
the	O
clean	O
syntax	O
that	O
is	O
CoffeeScript	B-Application
’s	O
hallmark.	O
"	O
</s>
<s>
Almost	O
everything	O
is	O
an	O
expression	O
in	O
CoffeeScript	B-Application
,	O
for	O
example	O
,	O
if	O
,	O
switch	O
and	O
for	O
expressions	O
(	O
which	O
have	O
no	O
return	O
value	O
in	O
JavaScript	B-Language
)	O
return	O
a	O
value	O
.	O
</s>
<s>
As	O
in	O
Perl	B-Language
,	O
these	O
control	O
statements	O
also	O
have	O
postfix	O
versions	O
;	O
for	O
example	O
,	O
if	O
can	O
also	O
be	O
written	O
in	O
consequent	O
if	O
condition	O
form	O
.	O
</s>
<s>
To	O
compute	O
the	O
body	O
mass	O
index	O
in	O
JavaScript	B-Language
,	O
one	O
could	O
write	O
:	O
</s>
<s>
With	O
CoffeeScript	B-Application
the	O
interval	O
is	O
directly	O
described	O
:	O
</s>
<s>
To	O
compute	O
the	O
greatest	O
common	O
divisor	O
of	O
two	O
integers	O
with	O
the	O
Euclidean	O
algorithm	O
,	O
in	O
JavaScript	B-Language
one	O
usually	O
needs	O
a	O
while	O
loop	O
:	O
</s>
<s>
Whereas	O
in	O
CoffeeScript	B-Application
one	O
can	O
use	O
until	O
instead	O
:	O
</s>
<s>
A	O
common	O
pre-es6	O
JavaScript	B-Language
snippet	O
using	O
the	O
jQuery	B-Language
library	I-Language
is	O
:	O
</s>
<s>
In	O
CoffeeScript	B-Application
,	O
the	O
function	O
keyword	O
is	O
replaced	O
by	O
the	O
->	O
symbol	O
,	O
and	O
indentation	O
is	O
used	O
instead	O
of	O
curly	O
braces	O
,	O
as	O
in	O
other	O
off-side	B-Language
rule	I-Language
languages	O
such	O
as	O
Python	B-Language
and	O
Haskell	B-Language
.	O
</s>
<s>
Thus	O
,	O
the	O
CoffeeScript	B-Application
equivalent	O
of	O
the	O
snippet	O
above	O
is	O
:	O
</s>
<s>
Ruby-style	O
string	O
interpolation	O
is	O
included	O
in	O
CoffeeScript	B-Application
.	O
</s>
<s>
Any	O
for	O
loop	O
can	O
be	O
replaced	O
by	O
a	O
list	B-Language
comprehension	I-Language
;	O
so	O
that	O
to	O
compute	O
the	O
squares	O
of	O
the	O
positive	O
odd	O
numbers	O
smaller	O
than	O
ten	O
(	O
i.e.	O
</s>
<s>
A	O
linear	B-Algorithm
search	I-Algorithm
can	O
be	O
implemented	O
with	O
a	O
one-liner	O
using	O
the	O
when	O
keyword	O
:	O
</s>
<s>
The	O
CoffeeScript	B-Application
compiler	O
has	O
been	O
self-hosting	O
since	O
version	O
0.5	O
and	O
is	O
available	O
as	O
a	O
Node.js	B-Language
utility	O
;	O
however	O
,	O
the	O
core	O
compiler	O
does	O
not	O
rely	O
on	O
Node.js	B-Language
and	O
can	O
be	O
run	O
in	O
any	O
JavaScript	B-Language
environment	O
.	O
</s>
<s>
One	O
alternative	O
to	O
the	O
Node.js	B-Language
utility	O
is	O
the	O
Coffee	O
Maven	B-Language
Plugin	O
,	O
a	O
plugin	O
for	O
the	O
Apache	B-Language
Maven	I-Language
build	O
system	O
.	O
</s>
<s>
The	O
plugin	O
uses	O
the	O
Rhino	B-Language
JavaScript	B-Language
engine	O
written	O
in	O
Java	B-Language
.	O
</s>
<s>
The	O
official	O
site	O
at	O
CoffeeScript.org	B-Application
has	O
a	O
"	O
Try	O
CoffeeScript	B-Application
"	O
button	O
in	O
the	O
menu	O
bar	O
;	O
clicking	O
it	O
opens	O
a	O
modal	O
window	O
in	O
which	O
users	O
can	O
enter	O
CoffeeScript	B-Application
,	O
see	O
the	O
JavaScript	B-Language
output	O
,	O
and	O
run	O
it	O
directly	O
in	O
the	O
browser	O
.	O
</s>
<s>
Source	O
maps	O
allow	O
users	O
to	O
debug	O
their	O
CoffeeScript	B-Application
code	O
directly	O
,	O
supporting	O
CoffeeScript	B-Application
tracebacks	O
on	O
run	O
time	O
errors	O
.	O
</s>
<s>
CoffeeScript	B-Application
supports	O
a	O
form	O
of	O
Literate	B-Application
Programming	I-Application
,	O
using	O
the	O
.coffee.md	O
or	O
.litcoffee	O
file	O
extension	O
.	O
</s>
<s>
This	O
allows	O
CoffeeScript	B-Application
source	O
code	O
to	O
be	O
written	O
in	O
Markdown	O
.	O
</s>
<s>
Iced	O
CoffeeScript	B-Application
is	O
a	O
superset	O
of	O
CoffeeScript	B-Application
which	O
adds	O
two	O
new	O
keywords	O
:	O
await	O
and	O
defer	O
.	O
</s>
<s>
These	O
additions	O
simplify	O
asynchronous	O
control	O
flow	O
,	O
making	O
the	O
code	O
look	O
more	O
like	O
a	O
procedural	B-Application
programming	I-Application
language	I-Application
,	O
eliminating	O
the	O
call-back	O
chain	O
.	O
</s>
<s>
On	O
September	O
13	O
,	O
2012	O
,	O
Dropbox	B-Application
announced	O
that	O
their	O
browser-side	O
code	O
base	O
had	O
been	O
rewritten	O
from	O
JavaScript	B-Language
to	O
CoffeeScript	B-Application
,	O
however	O
it	O
was	O
migrated	O
to	O
TypeScript	B-Language
in	O
2017	O
.	O
</s>
<s>
GitHub	B-Application
's	O
internal	O
style	O
guide	O
once	O
said	O
"	O
write	O
new	O
JS	O
in	O
CoffeeScript	B-Application
"	O
,	O
though	O
it	O
no	O
longer	O
does	O
,	O
and	O
their	O
Atom	B-Application
text	I-Application
editor	I-Application
was	O
also	O
written	O
in	O
the	O
language	O
.	O
</s>
<s>
Pixel	B-Application
Game	I-Application
Maker	I-Application
MV	I-Application
makes	O
uses	O
of	O
CoffeeScript	B-Application
as	O
part	O
of	O
its	O
game	O
development	O
environment	O
.	O
</s>
