<s>
Babel	B-Language
is	O
a	O
free	B-Application
and	O
open-source	B-Application
JavaScript	B-Language
transcompiler	B-Language
that	O
is	O
mainly	O
used	O
to	O
convert	O
ECMAScript	O
2015+	O
(	O
ES6+	O
)	O
code	O
into	O
backwards-compatible	O
JavaScript	B-Language
code	O
that	O
can	O
be	O
run	O
by	O
older	O
JavaScript	B-Language
engines	I-Language
.	O
</s>
<s>
Developers	O
can	O
use	O
new	O
JavaScript	B-Language
language	I-Language
features	O
by	O
using	O
Babel	B-Language
to	O
convert	O
their	O
source	O
code	O
into	O
versions	O
of	O
JavaScript	B-Language
that	O
a	O
Web	B-Application
browser	I-Application
can	O
process	O
.	O
</s>
<s>
Babel	B-Language
is	O
used	O
to	O
compile	B-Language
TypeScript	B-Language
into	O
JavaScript	B-Language
.	O
</s>
<s>
The	O
core	O
version	O
of	O
Babel	B-Language
was	O
downloaded	O
5	O
million	O
times	O
a	O
month	O
in	O
2016	O
,	O
and	O
this	O
increased	O
to	O
16	O
million	O
times	O
a	O
week	O
in	O
2019	O
.	O
</s>
<s>
Babel	B-Language
plugins	O
transform	O
syntax	O
that	O
is	O
not	O
widely	O
supported	O
into	O
a	O
backward-compatible	O
version	O
.	O
</s>
<s>
For	O
example	O
,	O
arrow	B-General_Concept
functions	I-General_Concept
,	O
which	O
are	O
specified	O
in	O
ES6	O
,	O
are	O
converted	O
into	O
regular	O
function	O
declarations	O
.	O
</s>
<s>
Non-standard	O
JavaScript	B-Language
syntax	O
such	O
as	O
JSX	B-Language
can	O
also	O
be	O
transformed	O
.	O
</s>
<s>
Babel	B-Language
can	O
automatically	O
inject	O
polyfills	B-Protocol
provided	O
by	O
core-js	O
for	O
support	O
features	O
that	O
are	O
missing	O
entirely	O
from	O
JavaScript	B-Language
environments	O
.	O
</s>
<s>
For	O
example	O
,	O
static	O
methods	O
such	O
as	O
Array.from	O
and	O
built-ins	B-Application
such	O
as	O
Promise	O
are	O
available	O
only	O
in	O
ES6	O
and	O
above	O
,	O
but	O
they	O
can	O
be	O
used	O
in	O
older	O
environments	O
if	O
core-js	O
is	O
used	O
.	O
</s>
