<s>
A	O
virtual	B-General_Concept
DOM	I-General_Concept
is	O
a	O
lightweight	O
JavaScript	B-Language
representation	O
of	O
the	O
Document	B-General_Concept
Object	I-General_Concept
Model	I-General_Concept
(	O
DOM	B-General_Concept
)	O
used	O
in	O
declarative	O
web	O
frameworks	O
such	O
as	O
React	B-Application
,	O
Vue.js	B-Language
,	O
and	O
Elm	B-Language
.	O
</s>
<s>
Updating	O
the	O
virtual	B-General_Concept
DOM	I-General_Concept
is	O
comparatively	O
faster	O
than	O
updating	O
the	O
actual	O
DOM	B-General_Concept
(	O
via	O
JavaScript	B-Language
)	O
.	O
</s>
<s>
Thus	O
,	O
the	O
framework	O
is	O
free	O
to	O
make	O
necessary	O
changes	O
to	O
the	O
virtual	B-General_Concept
DOM	I-General_Concept
relatively	O
cheaply	O
.	O
</s>
<s>
The	O
framework	O
then	O
finds	O
the	O
differences	O
between	O
the	O
previous	O
virtual	B-General_Concept
DOM	I-General_Concept
and	O
the	O
current	O
one	O
,	O
and	O
only	O
makes	O
the	O
necessary	O
changes	O
to	O
the	O
actual	O
DOM	B-General_Concept
.	O
</s>
<s>
Svelte	B-Language
does	O
not	O
have	O
a	O
virtual	B-General_Concept
DOM	I-General_Concept
,	O
and	O
its	O
creator	O
Rich	O
Harris	O
calls	O
the	O
virtual	B-General_Concept
DOM	I-General_Concept
"	O
pure	O
overhead	O
"	O
.	O
</s>
<s>
Related	O
techniques	O
include	O
Ember.js	B-Language
'	O
Glimmer	O
and	O
Angular	B-Language
's	O
incremental	O
DOM	B-General_Concept
.	O
</s>
