Js Fundamentals - Conditional if

Question 1

Boolean Conversions

Answer 1

Boolean conversion
The if (…) statement evaluates the expression in its parentheses and converts the result to a boolean.

Let’s recall the conversion rules from the chapter Type Conversions:

A number 0, an empty string “”, null, undefined, and NaN all become false. Because of that they are called “falsy” values.
Other values become true, so they are called “truthy”.

Question 2

The if statement may contain an optional “else” block. It executes when the condition is falsy.

Answer 2

Sometimes, we’d like to test several variants of a condition. The else if clause lets us do that.

Question 3

A complex ternary operator expression

Answer 3

if (age < 3) {
  message = 'Hi, baby!';
} else if (age < 18) {
  message = 'Hello!';
} else if (age < 100) {
  message = 'Greetings!';
} else {
  message = 'What an unusual age!';
}