Rewrite "if" into "switch"
importance: 4
Rewrite the code below using a single switch
statement:
let
a =
+
prompt
(
'a?'
,
''
)
;
if
(
a ==
0
)
{
alert
(
0
)
;
}
if
(
a ==
1
)
{
alert
(
1
)
;
}
if
(
a ==
2
||
a ==
3
)
{
alert
(
'2,3'
)
;
}
The first two checks turn into two case
. The third check is split into two cases:
let
a =
+
prompt
(
'a?'
,
''
)
;
switch
(
a)
{
case
0
:
alert
(
0
)
;
break
;
case
1
:
alert
(
1
)
;
break
;
case
2
:
case
3
:
alert
(
'2,3'
)
;
break
;
}
Please note: the break
at the bottom is not required. But we put it to make the code future-proof.
In the future, there is a chance that we’d want to add one more case
, for example case 4
. And if we forget to add a break before it, at the end of case 3
, there will be an error. So that’s a kind of self-insurance.