<s>
D3.js	B-Language
(	O
also	O
known	O
as	O
D3	O
,	O
short	O
for	O
Data-Driven	B-Language
Documents	I-Language
)	O
is	O
a	O
JavaScript	B-Language
library	I-Language
for	O
producing	O
dynamic	O
,	O
interactive	O
data	B-Application
visualizations	I-Application
in	O
web	B-Application
browsers	I-Application
.	O
</s>
<s>
It	O
makes	O
use	O
of	O
Scalable	B-Application
Vector	I-Application
Graphics	I-Application
(	O
SVG	B-Application
)	O
,	O
HTML5	B-Application
,	O
and	O
Cascading	B-Language
Style	I-Language
Sheets	I-Language
(	O
CSS	B-Language
)	O
standards	O
.	O
</s>
<s>
There	O
have	O
been	O
various	O
previous	O
attempts	O
to	O
bring	O
data	B-Application
visualization	I-Application
to	O
web	B-Application
browsers	I-Application
.	O
</s>
<s>
The	O
most	O
notable	O
examples	O
were	O
the	O
Prefuse	B-Language
,	O
Flare	O
,	O
and	O
Protovis	O
toolkits	O
,	O
which	O
can	O
all	O
be	O
considered	O
as	O
direct	O
predecessors	O
of	O
D3.js	B-Language
.	O
</s>
<s>
Prefuse	B-Language
was	O
a	O
visualization	O
toolkit	O
created	O
in	O
2005	O
that	O
required	O
usage	O
of	O
Java	B-Device
,	O
and	O
visualizations	O
were	O
rendered	O
within	O
browsers	B-Application
with	O
a	O
Java	B-Device
plug-in	O
.	O
</s>
<s>
Flare	O
was	O
a	O
similar	O
toolkit	O
from	O
2007	O
that	O
used	O
ActionScript	B-Operating_System
,	O
and	O
required	O
a	O
Flash	O
plug-in	O
for	O
rendering	O
.	O
</s>
<s>
In	O
2009	O
,	O
based	O
on	O
the	O
experience	O
of	O
developing	O
and	O
utilizing	O
Prefuse	B-Language
and	O
Flare	O
,	O
Jeffrey	O
Heer	O
,	O
Mike	O
Bostock	O
,	O
and	O
Vadim	O
Ogievetsky	O
of	O
Stanford	O
University	O
's	O
Stanford	O
Visualization	O
Group	O
created	O
Protovis	O
,	O
a	O
JavaScript	B-Language
library	I-Language
to	O
generate	O
SVG	B-Application
graphics	O
from	O
data	O
.	O
</s>
<s>
The	O
library	O
was	O
known	O
to	O
data	B-Application
visualization	I-Application
practitioners	O
and	O
academics	O
.	O
</s>
<s>
In	O
2011	O
,	O
the	O
development	O
of	O
Protovis	O
was	O
stopped	O
to	O
focus	O
on	O
a	O
new	O
project	O
,	O
D3.js	B-Language
.	O
</s>
<s>
Informed	O
by	O
experiences	O
with	O
Protovis	O
,	O
Bostock	O
,	O
along	O
with	O
Heer	O
and	O
Ogievetsky	O
,	O
developed	O
D3.js	B-Language
to	O
provide	O
a	O
more	O
expressive	O
framework	O
that	O
,	O
at	O
the	O
same	O
time	O
,	O
focuses	O
on	O
web	O
standards	O
and	O
provides	O
improved	O
performance	O
.	O
</s>
<s>
The	O
D3.js	B-Language
library	O
uses	O
pre-built	O
functions	O
to	O
select	O
elements	O
,	O
create	O
SVG	B-Application
objects	O
,	O
style	O
them	O
,	O
or	O
add	O
transitions	O
,	O
dynamic	O
effects	O
,	O
or	O
tooltips	O
.	O
</s>
<s>
These	O
objects	O
can	O
also	O
be	O
styled	O
using	O
CSS	B-Language
.	O
</s>
<s>
Large	O
datasets	O
can	O
be	O
bound	O
to	O
SVG	B-Application
objects	O
using	O
D3.js	B-Language
functions	O
to	O
generate	O
text/graphic	O
charts	O
and	O
diagrams	O
.	O
</s>
<s>
The	O
data	O
can	O
be	O
in	O
various	O
formats	O
such	O
as	O
JSON	B-General_Concept
,	O
comma-separated	O
values	O
(	O
CSV	O
)	O
or	O
geoJSON	B-General_Concept
,	O
but	O
,	O
if	O
required	O
,	O
JavaScript	B-Language
functions	O
can	O
be	O
written	O
to	O
read	O
other	O
data	O
formats	O
.	O
</s>
<s>
The	O
central	O
principle	O
of	O
D3.js	B-Language
design	O
is	O
to	O
enable	O
the	O
programmer	O
to	O
first	O
use	O
a	O
CSS-style	O
selector	O
to	O
select	O
a	O
given	O
set	O
of	O
Document	B-General_Concept
Object	I-General_Concept
Model	I-General_Concept
(	O
DOM	B-General_Concept
)	O
nodes	O
,	O
then	O
use	O
operators	O
to	O
manipulate	O
them	O
in	O
a	O
similar	O
manner	O
to	O
jQuery	B-Language
.	O
</s>
<s>
This	O
process	O
of	O
modifying	O
,	O
creating	O
and	O
removing	O
HTML	O
elements	O
can	O
be	O
made	O
dependent	O
on	O
data	O
,	O
which	O
is	O
the	O
basic	O
concept	O
of	O
D3.js	B-Language
.	O
</s>
<s>
D3.js	B-Language
loads	O
a	O
given	O
dataset	O
,	O
then	O
,	O
for	O
each	O
of	O
its	O
elements	O
,	O
creates	O
an	O
SVG	B-Application
object	O
with	O
associated	O
properties	O
(	O
shape	O
,	O
colors	O
,	O
values	O
)	O
and	O
behaviors	O
(	O
transitions	O
,	O
events	O
)	O
.	O
</s>
<s>
Generated	O
SVG	B-Application
graphics	O
are	O
designed	O
according	O
to	O
the	O
provided	O
data	O
.	O
</s>
<s>
Once	O
a	O
dataset	O
is	O
bound	O
to	O
a	O
document	O
,	O
use	O
of	O
D3.js	B-Language
typically	O
follows	O
a	O
pattern	O
wherein	O
an	O
explicit	O
.enter( )	O
function	O
,	O
an	O
implicit	O
"	O
update	O
,	O
"	O
and	O
an	O
explicit	O
.exit( )	O
function	O
is	O
invoked	O
for	O
each	O
item	O
in	O
the	O
bound	O
dataset	O
.	O
</s>
<s>
Any	O
methods	B-Language
chained	I-Language
after	O
the	O
.enter( )	O
command	O
will	O
be	O
called	O
for	O
each	O
item	O
in	O
the	O
dataset	O
not	O
already	O
represented	O
by	O
a	O
DOM	B-General_Concept
node	O
in	O
the	O
selection	O
(	O
the	O
previous	O
selectAll( )	O
)	O
.	O
</s>
<s>
The	O
D3.js	B-Language
documentation	O
provides	O
several	O
examples	O
of	O
how	O
this	O
works	O
.	O
</s>
