if (boolean expression)
statement
or
if (boolean expression)
statement
else
statement
Example:
if ((x == y) && (z >= 3))
{
r = 23.0;
z--;
}
else if (x > y)
{
r = -4.0;
x++;
}
else r = 10.2;
In some programming languages there is also a keyword elseif
, but not in JavaScript: use else
and then if
, as in the example.
switch (expression)
{
case value1: statements
case value2: statements
...
default: statements
}
The expression is evaluated. If the result matches any of the case
values, statement execution begins at that point and continues through all the other cases and the default section unless something prevents that. Usually the statement break;
makes execution jump out of the switch statement before the next case is reached. It is important to remember to break out like this if that is required.
The default
section is optional. Execution starts there if none of the values matches the result of the expression.
Example (text editor - user has pressed a key):
switch (keyCode)
{
case insKey: insert ();
break;
case backKey:
case delKey: delete ();
break;
default: append (keyCode);
}
These rules are more flexible than in other languages (eg, C or Java).