Comparators

Lets now focus on the conditional part:

  1. if (country === "France") {
  2.     ...
  3. }

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.

  1. 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.