“Avaliação de curto-circuito, uso de || operador” Respostas de código

Avaliação de curto-circuito, uso de || operador

/*
Truthy and Falsy Assignment:
Truthy and falsy evaluations open a world of short-hand possibilities!

Say you have a website and want to take a user’s username to make a 
personalized greeting. Sometimes, the user does not have an account, 
making the username variable falsy. The code below checks if 
username is defined and assigns a default string if it is not:
*/




let username = '';
let defaultName;
 
if (username) {
  defaultName = username;
} else {
  defaultName = 'Stranger';
}
 
console.log(defaultName); // Prints: Stranger
/*
If you combine your knowledge of logical operators you can use a SHORT-HAND
for the code above. In a boolean condition, JavaScript assigns the truthy 
value to a variable if you use the || operator in your assignment:
*/

let username = '';
let defaultName = username || 'Stranger';
 
console.log(defaultName); // Prints: Stranger

/*
Because || or statements check the left-hand condition first, the variable 
defaultName will be assigned the actual value of username if it is truthy, 
and it will be assigned the value of 'Stranger' 
if username is falsy. This concept is also referred to as short-circuit evaluation.
*/