<s>
Modernizr	B-Language
is	O
a	O
JavaScript	B-Language
library	I-Language
that	O
detects	O
the	O
features	O
available	O
in	O
a	O
user	O
's	O
browser	B-Application
.	O
</s>
<s>
This	O
lets	O
web	O
pages	O
avoid	O
unsupported	O
features	O
by	O
informing	O
the	O
user	O
their	O
browser	B-Application
is	O
n't	O
supported	O
or	O
loading	O
a	O
polyfill	B-Protocol
.	O
</s>
<s>
Modernizr	B-Language
aims	O
to	O
provide	O
feature	O
detection	O
in	O
a	O
consistent	O
and	O
easy	O
to	O
use	O
manner	O
that	O
discourages	O
the	O
use	O
of	O
failure-prone	O
browser	B-Protocol
sniffing	I-Protocol
.	O
</s>
<s>
Many	O
HTML5	B-Application
and	O
CSS	B-Language
3	I-Language
features	O
are	O
already	O
implemented	O
in	O
at	O
least	O
one	O
major	O
browser	B-Application
.	O
</s>
<s>
Modernizr	B-Language
determines	O
whether	O
the	O
user	O
's	O
browser	B-Application
has	O
implemented	O
a	O
given	O
feature	O
.	O
</s>
<s>
This	O
lets	O
developers	O
take	O
advantage	O
of	O
new	O
features	O
that	O
browsers	B-Application
support	O
,	O
yet	O
create	O
fallbacks	O
for	O
browsers	B-Application
that	O
lack	O
support	O
.	O
</s>
<s>
In	O
both	O
2010	O
and	O
2011	O
,	O
Modernizr	B-Language
won	O
the	O
.net	O
Award	O
for	O
Open	O
Source	O
App	O
of	O
the	O
Year	O
,	O
and	O
in	O
2011	O
one	O
of	O
its	O
lead	O
developers	O
,	O
Paul	O
Irish	O
,	O
won	O
the	O
Developer	O
of	O
the	O
Year	O
award	O
.	O
</s>
<s>
Modernizr	B-Language
uses	O
feature	O
detection	O
,	O
rather	O
than	O
checking	O
the	O
browser	B-Application
's	O
property	O
,	O
to	O
discern	O
what	O
a	O
browser	B-Application
can	O
and	O
cannot	O
do	O
.	O
</s>
<s>
It	O
considers	O
feature	O
detection	O
more	O
reliable	O
since	O
the	O
same	O
rendering	O
engine	O
may	O
not	O
necessarily	O
support	O
the	O
same	O
things	O
in	O
two	O
different	O
browsers	B-Application
using	O
that	O
engine	O
.	O
</s>
<s>
In	O
addition	O
,	O
some	O
users	O
change	O
their	O
user	O
agent	O
string	O
to	O
get	O
around	O
websites	O
that	O
block	O
features	O
for	O
browsers	B-Application
with	O
specific	O
user	O
agent	O
settings	O
,	O
despite	O
their	O
browsers	B-Application
having	O
the	O
necessary	O
capabilities	O
.	O
</s>
<s>
Modernizr	B-Language
offers	O
tests	O
for	O
more	O
than	O
250	O
features	O
,	O
then	O
creates	O
a	O
JavaScript	B-Language
object	O
(	O
named	O
"	O
Modernizr	B-Language
"	O
)	O
that	O
contains	O
the	O
results	O
of	O
these	O
tests	O
as	O
boolean	O
properties	O
.	O
</s>
<s>
It	O
also	O
adds	O
classes	O
to	O
the	O
HTML	B-Language
element	O
based	O
on	O
what	O
features	O
are	O
and	O
are	O
not	O
natively	O
supported	O
.	O
</s>
<s>
To	O
perform	O
feature	O
detection	O
tests	O
,	O
Modernizr	B-Language
often	O
creates	O
an	O
element	O
,	O
sets	O
a	O
specific	O
style	O
instruction	O
on	O
that	O
element	O
and	O
then	O
immediately	O
tries	O
to	O
retrieve	O
that	O
setting	O
.	O
</s>
<s>
Web	B-Application
browsers	I-Application
that	O
understand	O
the	O
instruction	O
will	O
return	O
something	O
sensible	O
;	O
browsers	B-Application
that	O
do	O
n't	O
understand	O
it	O
will	O
return	O
nothing	O
or	O
"	O
undefined	O
"	O
.	O
</s>
<s>
Modernizr	B-Language
uses	O
the	O
result	O
to	O
assess	O
whether	O
that	O
feature	O
is	O
supported	O
by	O
the	O
web	B-Application
browser	I-Application
.	O
</s>
<s>
Many	O
tests	O
in	O
the	O
documentation	O
come	O
with	O
a	O
small	O
code	O
sample	O
to	O
illustrate	O
how	O
a	O
specific	O
test	O
can	O
be	O
used	O
in	O
web	O
development	O
workflow	B-Operating_System
.	O
</s>
<s>
When	O
it	O
runs	O
,	O
it	O
creates	O
a	O
global	O
object	O
called	O
Modernizr	B-Language
that	O
contains	O
a	O
set	O
of	O
Boolean	O
properties	O
for	O
each	O
feature	O
it	O
can	O
detect	O
.	O
</s>
<s>
For	O
example	O
,	O
if	O
a	O
browser	B-Application
supports	O
the	O
canvas	O
API	O
,	O
the	O
Modernizr.canvas	O
property	O
will	O
be	O
true	O
.	O
</s>
<s>
If	O
the	O
browser	B-Application
does	O
not	O
support	O
the	O
canvas	O
API	O
,	O
the	O
Modernizr.canvas	O
property	O
will	O
be	O
false	O
:	O
</s>
<s>
The	O
library	B-Library
is	O
simply	O
a	O
feature-detection	O
method	O
and	O
as	O
such	O
,	O
does	O
not	O
add	O
missing	O
functionality	O
to	O
older	O
browsers	B-Application
.	O
</s>
