Lets now focus on the conditional part:
if (country === "France") {
...
}
The conditional part is the variable country
followed by the three equal signs (===
). Three equal signs tests if the variable country
has both the correct value (France
) and also the correct type (String
). You can test conditions with double equal signs, too, however a conditional such as if (x == 5)
would then return true for both var x = 5;
and var x = "5";
. Depending on what your program is doing, this could make quite a difference. It is highly recommended as a best practice that you always compare equality with three equal signs (===
and !==
) instead of two (==
and !=
).
Other conditional test:
x > a
: is x bigger than a?x < a
: is x less than a?x <= a
: is x less than or equal to a?x >=a
: is x greater than or equal to a?x != a
: is x not a?x
: does x exist?
{% exercise %}
Add a condition to change the value of a
to the number 10 if x
is bigger than 5.
{% initial %}
var x = 6;
var a = 0;
{% solution %}
var x = 6;
var a = 0;
if (x > 5) { a = 10; } {% validation %} assert(a === 10); {% endexercise %}
##Logical Comparison
In order to avoid the if-else hassle, simple logical comparisons can be utilised.
var topper = (marks > 85) ? "YES" : "NO";
In the above example, ?
is a logical operator. The code says that if the value of marks is greater than 85 i.e. marks > 85
, then topper = YES
; otherwise topper = NO
. Basically, if the comparison condition proves true, the first argument is accessed and if the comparison condition is false , the second argument is accessed.