<s>
Ajax	B-General_Concept
(	O
also	O
AJAX	B-General_Concept
;	O
short	O
for	O
"	O
Asynchronous	B-General_Concept
JavaScript	I-General_Concept
and	I-General_Concept
XML	I-General_Concept
"	O
)	O
is	O
a	O
set	O
of	O
web	O
development	O
techniques	O
that	O
uses	O
various	O
web	O
technologies	O
on	O
the	O
client-side	B-Operating_System
to	O
create	O
asynchronous	B-Architecture
web	B-Application
applications	I-Application
.	O
</s>
<s>
With	O
Ajax	B-General_Concept
,	O
web	B-Application
applications	I-Application
can	O
send	O
and	O
retrieve	O
data	O
from	O
a	O
server	B-Application
asynchronously	O
(	O
in	O
the	O
background	O
)	O
without	O
interfering	O
with	O
the	O
display	O
and	O
behaviour	O
of	O
the	O
existing	O
page	O
.	O
</s>
<s>
By	O
decoupling	O
the	O
data	B-General_Concept
interchange	I-General_Concept
layer	O
from	O
the	O
presentation	O
layer	O
,	O
Ajax	B-General_Concept
allows	O
web	O
pages	O
and	O
,	O
by	O
extension	O
,	O
web	B-Application
applications	I-Application
,	O
to	O
change	O
content	O
dynamically	O
without	O
the	O
need	O
to	O
reload	O
the	O
entire	O
page	O
.	O
</s>
<s>
In	O
practice	O
,	O
modern	O
implementations	O
commonly	O
utilize	O
JSON	B-General_Concept
instead	O
of	O
XML	B-Protocol
.	O
</s>
<s>
Ajax	B-General_Concept
is	O
not	O
a	O
technology	O
,	O
but	O
rather	O
a	O
programming	O
concept	O
.	O
</s>
<s>
HTML	B-Language
and	O
CSS	B-Language
can	O
be	O
used	O
in	O
combination	O
to	O
mark	O
up	O
and	O
style	O
information	O
.	O
</s>
<s>
The	O
webpage	O
can	O
be	O
modified	O
by	O
JavaScript	B-Language
to	O
dynamically	O
display	O
—	O
and	O
allow	O
the	O
user	O
to	O
interact	O
with	O
the	O
new	O
information	O
.	O
</s>
<s>
The	O
built-in	O
XMLHttpRequest	B-Protocol
object	O
is	O
used	O
to	O
execute	O
Ajax	B-General_Concept
on	O
webpages	O
,	O
allowing	O
websites	O
to	O
load	O
content	O
onto	O
the	O
screen	O
without	O
refreshing	O
the	O
page	O
.	O
</s>
<s>
Ajax	B-General_Concept
is	O
not	O
a	O
new	O
technology	O
,	O
nor	O
is	O
it	O
a	O
new	O
language	O
.	O
</s>
<s>
In	O
the	O
early-to-mid	O
1990s	O
,	O
most	O
Websites	O
were	O
based	O
on	O
complete	O
HTML	B-Language
pages	O
.	O
</s>
<s>
Each	O
user	O
action	O
required	O
a	O
complete	O
new	O
page	O
to	O
be	O
loaded	O
from	O
the	O
server	B-Application
.	O
</s>
<s>
This	O
placed	O
additional	O
load	O
on	O
the	O
server	B-Application
and	O
made	O
bandwidth	O
a	O
limiting	O
factor	O
in	O
performance	O
.	O
</s>
<s>
In	O
1996	O
,	O
the	O
iframe	O
tag	O
was	O
introduced	O
by	O
Internet	B-Application
Explorer	I-Application
;	O
like	O
the	O
object	O
element	O
,	O
it	O
can	O
load	O
or	O
fetch	O
content	O
asynchronously	O
.	O
</s>
<s>
In	O
1998	O
,	O
the	O
Microsoft	O
Outlook	B-Protocol
Web	I-Protocol
Access	I-Protocol
team	O
developed	O
the	O
concept	O
behind	O
the	O
XMLHttpRequest	B-Protocol
scripting	O
object	O
.	O
</s>
<s>
It	O
appeared	O
as	O
XMLHTTP	B-Protocol
in	O
the	O
second	O
version	O
of	O
the	O
MSXML	B-Application
library	O
,	O
which	O
shipped	O
with	O
Internet	B-Protocol
Explorer	I-Protocol
5.0	I-Protocol
in	O
March	O
1999	O
.	O
</s>
<s>
The	O
functionality	O
of	O
the	O
Windows	O
XMLHTTP	B-Protocol
ActiveX	B-Application
control	I-Application
in	O
IE	B-Protocol
5	I-Protocol
was	O
later	O
implemented	O
by	O
Mozilla	B-Application
Firefox	I-Application
,	O
Safari	B-Application
,	O
Opera	B-Application
,	O
Google	B-Application
Chrome	I-Application
,	O
and	O
other	O
browsers	O
as	O
the	O
XMLHttpRequest	B-Protocol
JavaScript	B-Language
object	O
.	O
</s>
<s>
Microsoft	O
adopted	O
the	O
native	O
XMLHttpRequest	B-Protocol
model	O
as	O
of	O
Internet	B-Application
Explorer	I-Application
7	I-Application
.	O
</s>
<s>
The	O
ActiveX	B-Application
version	O
is	O
still	O
supported	O
in	O
Internet	B-Application
Explorer	I-Application
,	O
but	O
not	O
in	O
Microsoft	B-Application
Edge	I-Application
.	O
</s>
<s>
The	O
utility	O
of	O
these	O
background	O
HTTP	B-Protocol
requests	I-Protocol
and	O
asynchronous	B-Architecture
Web	O
technologies	O
remained	O
fairly	O
obscure	O
until	O
it	O
started	O
appearing	O
in	O
large	O
scale	O
online	B-Application
applications	I-Application
such	O
as	O
Outlook	B-Protocol
Web	I-Protocol
Access	I-Protocol
(	O
2000	O
)	O
and	O
Oddpost	B-Application
(	O
2002	O
)	O
.	O
</s>
<s>
Google	B-Application
made	O
a	O
wide	O
deployment	O
of	O
standards-compliant	O
,	O
cross	B-Architecture
browser	I-Architecture
Ajax	B-General_Concept
with	O
Gmail	B-Application
(	O
2004	O
)	O
and	O
Google	B-Application
Maps	I-Application
(	O
2005	O
)	O
.	O
</s>
<s>
In	O
October	O
2004	O
com	O
's	O
public	O
beta	O
release	O
was	O
among	O
the	O
first	O
large-scale	O
e-commerce	O
uses	O
of	O
what	O
their	O
developers	O
at	O
that	O
time	O
called	O
"	O
the	O
xml	B-Protocol
http	B-Protocol
thing	O
"	O
.	O
</s>
<s>
This	O
increased	O
interest	O
in	O
Ajax	B-General_Concept
among	O
web	O
program	O
developers	O
.	O
</s>
<s>
The	O
term	O
AJAX	B-General_Concept
was	O
publicly	O
used	O
on	O
18	O
February	O
2005	O
by	O
Jesse	O
James	O
Garrett	O
in	O
an	O
article	O
titled	O
Ajax	B-General_Concept
:	O
A	O
New	O
Approach	O
to	O
Web	B-Application
Applications	I-Application
,	O
based	O
on	O
techniques	O
used	O
on	O
Google	B-Application
pages	O
.	O
</s>
<s>
On	O
5	O
April	O
2006	O
,	O
the	O
World	O
Wide	O
Web	O
Consortium	O
(	O
W3C	O
)	O
released	O
the	O
first	O
draft	O
specification	O
for	O
the	O
XMLHttpRequest	B-Protocol
object	O
in	O
an	O
attempt	O
to	O
create	O
an	O
official	O
Web	O
standard	O
.	O
</s>
<s>
The	O
latest	O
draft	O
of	O
the	O
XMLHttpRequest	B-Protocol
object	O
was	O
published	O
on	O
6	O
October	O
2016	O
,	O
and	O
the	O
XMLHttpRequest	B-Protocol
specification	O
is	O
now	O
a	O
living	O
standard	O
.	O
</s>
<s>
The	O
term	O
Ajax	B-General_Concept
has	O
come	O
to	O
represent	O
a	O
broad	O
group	O
of	O
Web	O
technologies	O
that	O
can	O
be	O
used	O
to	O
implement	O
a	O
Web	B-Application
application	I-Application
that	O
communicates	O
with	O
a	O
server	B-Application
in	O
the	O
background	O
,	O
without	O
interfering	O
with	O
the	O
current	O
state	O
of	O
the	O
page	O
.	O
</s>
<s>
In	O
the	O
article	O
that	O
coined	O
the	O
term	O
Ajax	B-General_Concept
,	O
Jesse	O
James	O
Garrett	O
explained	O
that	O
the	O
following	O
technologies	O
are	O
incorporated	O
:	O
</s>
<s>
Since	O
then	O
,	O
however	O
,	O
there	O
have	O
been	O
a	O
number	O
of	O
developments	O
in	O
the	O
technologies	O
used	O
in	O
an	O
Ajax	B-General_Concept
application	O
,	O
and	O
in	O
the	O
definition	O
of	O
the	O
term	O
Ajax	B-General_Concept
itself	O
.	O
</s>
<s>
XML	B-Protocol
is	O
no	O
longer	O
required	O
for	O
data	B-General_Concept
interchange	I-General_Concept
and	O
,	O
therefore	O
,	O
XSLT	B-Application
is	O
no	O
longer	O
required	O
for	O
the	O
manipulation	O
of	O
data	O
.	O
</s>
<s>
JavaScript	B-General_Concept
Object	I-General_Concept
Notation	I-General_Concept
(	O
JSON	B-General_Concept
)	O
is	O
often	O
used	O
as	O
an	O
alternative	O
format	O
for	O
data	B-General_Concept
interchange	I-General_Concept
,	O
although	O
other	O
formats	O
such	O
as	O
preformatted	O
HTML	B-Language
or	O
plain	O
text	O
can	O
also	O
be	O
used	O
.	O
</s>
<s>
A	O
variety	O
of	O
popular	O
JavaScript	B-Language
libraries	I-Language
,	O
including	O
JQuery	O
,	O
include	O
abstractions	O
to	O
assist	O
in	O
executing	O
Ajax	B-General_Concept
requests	O
.	O
</s>
<s>
An	O
example	O
of	O
a	O
simple	O
Ajax	B-General_Concept
request	O
using	O
the	O
GET	O
method	O
,	O
written	O
in	O
JavaScript	B-Language
.	O
</s>
<s>
get-ajax-data.js	O
:	O
</s>
<s>
send-ajax-data.php	O
:	O
</s>
<s>
Fetch	O
is	O
a	O
native	O
JavaScript	B-Language
API	O
.	O
</s>
<s>
According	O
to	O
,	O
"	O
Fetch	O
makes	O
it	O
easier	O
to	O
make	O
web	O
requests	O
and	O
handle	O
responses	O
than	O
with	O
the	O
older	O
XMLHttpRequest.	O
"	O
</s>
<s>
Fetch	O
relies	O
on	O
JavaScript	B-Language
.	O
</s>
<s>
The	O
fetch	O
specification	O
differs	O
from	O
Ajax	B-General_Concept
in	O
the	O
following	O
significant	O
ways	O
:	O
</s>
<s>
The	O
Promise	O
returned	O
from	O
fetch( )	O
wo	O
n't	O
reject	O
on	O
HTTP	B-Protocol
error	O
status	O
even	O
if	O
the	O
response	O
is	O
an	O
HTTP	B-Protocol
404	O
or	O
500	O
.	O
</s>
<s>
Instead	O
,	O
as	O
soon	O
as	O
the	O
server	B-Application
responds	O
with	O
headers	O
,	O
the	O
Promise	O
will	O
resolve	O
normally	O
(	O
with	O
the	O
ok	O
property	O
of	O
the	O
response	O
set	O
to	O
false	O
if	O
the	O
response	O
is	O
n't	O
in	O
the	O
range	O
200	O
–	O
299	O
)	O
,	O
and	O
it	O
will	O
only	O
reject	O
on	O
network	O
failure	O
or	O
if	O
anything	O
prevented	O
the	O
request	O
from	O
completing	O
.	O
</s>
<s>
Firefox	B-Application
changed	O
since	O
61.0b13	O
.	O
)	O
</s>
