<s>
Leaflet	B-Language
is	O
an	O
open	O
source	O
JavaScript	B-Language
library	I-Language
used	O
to	O
build	O
web	O
mapping	O
applications	B-Application
.	O
</s>
<s>
First	O
released	O
in	O
2011	O
,	O
it	O
supports	O
most	O
mobile	O
and	O
desktop	O
platforms	O
,	O
supporting	O
HTML5	B-Application
and	O
CSS3	O
.	O
</s>
<s>
Among	O
its	O
users	O
are	O
FourSquare	B-Application
,	O
Pinterest	B-Application
and	O
Flickr	B-Algorithm
.	O
</s>
<s>
Leaflet	B-Language
allows	O
developers	O
without	O
a	O
GIS	O
background	O
to	O
very	O
easily	O
display	O
tiled	O
web	O
maps	O
hosted	O
on	O
a	O
public	O
server	O
,	O
with	O
optional	O
tiled	O
overlays	O
.	O
</s>
<s>
It	O
can	O
load	O
feature	O
data	O
from	O
GeoJSON	B-General_Concept
files	O
,	O
style	O
it	O
and	O
create	O
interactive	O
layers	O
,	O
such	O
as	O
markers	O
with	O
popups	O
when	O
clicked	O
.	O
</s>
<s>
A	O
typical	O
use	O
of	O
Leaflet	B-Language
involves	O
binding	O
a	O
Leaflet	B-Language
"	O
map	O
"	O
element	O
to	O
an	O
HTML	O
element	O
such	O
as	O
a	O
div	B-General_Concept
.	O
</s>
<s>
A	O
unique	O
feature	O
of	O
leaflet	B-Language
is	O
displaying	O
maps	O
in	O
non-spherical	O
Mercator	O
projections	O
.	O
</s>
<s>
The	O
Leaflet	B-Language
library	B-Library
itself	O
is	O
accessible	O
through	O
the	O
variable	O
L	O
.	O
</s>
<s>
Leaflet	B-Language
supports	O
Web	B-Application
Map	I-Application
Service	I-Application
(	O
WMS	B-Application
)	O
layers	O
,	O
GeoJSON	B-General_Concept
layers	O
,	O
Vector	O
layers	O
and	O
Tile	O
layers	O
natively	O
.	O
</s>
<s>
Many	O
other	O
types	O
of	O
layers	O
are	O
supported	O
via	O
plugins	B-Application
.	O
</s>
<s>
Like	O
other	O
web	O
map	O
libraries	O
,	O
the	O
basic	O
display	O
model	O
implemented	O
by	O
Leaflet	B-Language
is	O
one	O
basemap	O
,	O
plus	O
zero	O
or	O
more	O
translucent	O
overlays	O
,	O
with	O
zero	O
or	O
more	O
vector	O
objects	O
displayed	O
on	O
top	O
.	O
</s>
<s>
The	O
major	O
Leaflet	B-Language
object	O
types	O
are	O
:	O
</s>
<s>
There	O
is	O
also	O
a	O
variety	O
of	O
utility	O
classes	O
such	O
as	O
interfaces	O
for	O
managing	O
projections	O
,	O
transformations	O
and	O
interacting	O
with	O
the	B-General_Concept
DOM	I-General_Concept
.	O
</s>
<s>
Leaflet	B-Language
has	O
core	O
support	O
for	O
multiple	O
GIS	O
standard	O
formats	O
,	O
with	O
others	O
supported	O
in	O
plugins	B-Application
.	O
</s>
<s>
Standard	O
Support	O
GeoJSON	B-General_Concept
Good	O
,	O
core	O
support	O
through	O
the	O
geoJson	B-General_Concept
function	O
KML	O
,	O
CSV	O
,	O
WKT	O
,	O
TopoJSON	O
,	O
GPX	O
Supported	O
in	O
Leaflet-Omnivore	O
plugin	B-Application
WMS	B-Application
Core	O
support	O
through	O
the	O
TileLayer.WMS	O
subtype	O
WFS	O
Not	O
supported	O
,	O
although	O
3rd	O
party	O
plugins	B-Application
exist	O
.	O
</s>
<s>
Leaflet	B-Language
0.7	O
supports	O
Chrome	O
,	O
Firefox	O
,	O
Safari	O
5+	O
,	O
Opera	O
12+	O
and	O
IE	O
7-11	O
.	O
</s>
<s>
Leaflet	B-Language
is	O
directly	O
comparable	O
with	O
OpenLayers	B-Language
,	O
as	O
both	O
are	O
open	O
source	O
,	O
client-side	O
only	O
JavaScript	B-Language
libraries	I-Language
.	O
</s>
<s>
The	O
library	B-Library
as	O
a	O
whole	O
is	O
much	O
smaller	O
,	O
around	O
7,000	O
lines	O
of	O
code	O
compared	O
to	O
OpenLayers	B-Language
 '	O
230,000	O
(	O
as	O
of	O
2015	O
)	O
.	O
</s>
<s>
It	O
has	O
a	O
smaller	O
code	O
footprint	O
than	O
OpenLayers	B-Language
(	O
around	O
123	O
KB	O
vs	O
423	O
KB	O
)	O
due	O
partly	O
to	O
its	O
modular	O
structure	O
.	O
</s>
<s>
The	O
code	O
base	O
is	O
newer	O
,	O
and	O
takes	O
advantage	O
of	O
recent	O
features	O
of	O
JavaScript	B-Language
,	O
plus	O
HTML5	B-Application
and	O
CSS3	O
.	O
</s>
<s>
However	O
,	O
Leaflet	B-Language
lacks	O
features	O
OpenLayers	B-Language
supports	O
,	O
such	O
as	O
Web	O
Feature	O
Service	O
(	O
WFS	O
)	O
and	O
native	O
support	O
for	O
projections	O
other	O
than	O
Google	O
Web	O
Mercator	O
(	O
EPSG	O
3857	O
)	O
.	O
</s>
<s>
It	O
is	O
also	O
comparable	O
to	O
the	O
proprietary	O
,	O
closed	O
source	O
Google	O
Maps	O
API	O
(	O
debuting	O
in	O
2005	O
)	O
and	O
Bing	O
Maps	O
API	O
,	O
both	O
of	O
which	O
incorporate	O
a	O
significant	O
server-side	O
component	O
to	O
provide	O
services	O
such	O
as	O
geocoding	B-Application
,	O
routing	B-Protocol
,	O
search	O
and	O
integration	O
with	O
features	O
such	O
as	O
Google	B-Application
Earth	I-Application
.	O
</s>
<s>
Leaflet	B-Language
began	O
life	O
in	O
2010	O
as	O
"	O
Web	O
Maps	O
API	O
"	O
,	O
a	O
JavaScript	B-Language
library	I-Language
for	O
the	O
CloudMade	O
mapping	O
provider	O
,	O
where	O
Agafonkin	O
worked	O
at	O
the	O
time	O
.	O
</s>
<s>
In	O
May	O
2011	O
,	O
CloudMade	O
announced	O
the	O
first	O
release	O
of	O
Leaflet	B-Language
,	O
built	O
from	O
scratch	O
but	O
using	O
parts	O
of	O
the	O
old	O
API	O
code	O
.	O
</s>
<s>
This	O
release	O
introduced	O
Retina	B-Operating_System
support	O
and	O
many	O
usability	O
and	O
user	O
experience	O
improvements	O
.	O
</s>
<s>
This	O
release	O
expanded	O
the	O
API	O
's	O
range	O
of	O
methods	O
and	O
events	O
,	O
improved	O
usability	O
,	O
and	O
added	O
GeoJSON	B-General_Concept
saving	O
.	O
</s>
<s>
Performance	O
improvements	O
in	O
all	O
aspects	O
of	O
the	O
library	B-Library
and	O
vector	O
layers	O
in	O
particular	O
.	O
</s>
<s>
In	O
March	O
2022	O
,	O
the	O
developer	O
urged	O
action	O
on	O
the	O
Russian	O
invasion	O
of	O
Ukraine	O
on	O
the	O
leafletjs	B-Language
website	O
.	O
</s>
