<s>
CodeMirror	B-Language
is	O
a	O
JavaScript	B-Language
component	O
that	O
provides	O
a	O
code	B-Application
editor	I-Application
in	O
the	O
browser	B-Application
.	O
</s>
<s>
It	O
has	O
a	O
rich	O
programming	O
API	B-Application
and	O
a	O
focus	O
on	O
extensibility	B-Architecture
.	O
</s>
<s>
The	O
first	O
version	O
of	O
the	O
editor	O
was	O
written	O
early	O
2007	O
,	O
for	O
the	O
console	O
in	O
the	O
Eloquent	O
JavaScript	B-Language
website	O
.	O
</s>
<s>
The	O
code	O
was	O
first	O
packaged	O
up	O
and	O
released	O
under	O
the	O
name	O
CodeMirror	B-Language
in	O
May	O
2007	O
.	O
</s>
<s>
This	O
version	O
was	O
based	O
on	O
the	O
contentEditable	O
feature	O
of	O
browsers	B-Application
.	O
</s>
<s>
In	O
late	O
2010	O
,	O
the	O
Ace	O
project	O
,	O
another	O
JavaScript-based	O
code	B-Application
editor	I-Application
,	O
pioneered	O
new	O
implementation	O
techniques	O
and	O
demonstrated	O
that	O
it	O
is	O
possible	O
,	O
even	O
in	O
JavaScript	B-Language
,	O
to	O
handle	O
documents	O
with	O
many	O
thousands	O
of	O
lines	O
without	O
degraded	O
performance	O
.	O
</s>
<s>
This	O
prompted	O
a	O
rewrite	O
of	O
CodeMirror	B-Language
along	O
the	O
same	O
principles	O
.	O
</s>
