In JavaScript, an empty array [] is considered a truthy value, meaning it's treated as true in a boolean context, resulting in unexpected comparisons when using the loose equality operator ==. This leads to [] == true returning true and [] == false returning false.
In the given code breakdown, console.log() prints output to the console, while the OR operator (||) returns the first truthy value from its operands. In JavaScript, empty arrays ([]) are considered falsy values, whereas non-empty arrays (['not falsey enough']) are considered truthy values.
This line of code uses the logical OR operator (||) to evaluate two expressions, an empty string ('') and a non-empty string ('unempty strings'). Due to how JavaScript handles falsy values, it will always log 'unempty strings' to the console, regardless of the value of the first expression.
The JavaScript code console.log(0 || 1) logs the result of the conditional expression 0 || 1 to the console, which evaluates to 1 because 1 is the first "truthy" value encountered. This is due to the || operator's behavior of returning the first truthy value it encounters.
The provided code uses the logical OR operator (||) to return an object with a default property set to true if the left side (a null value) is falsy. In this case, the expression returns { default: true } because null is considered falsy in JavaScript.
The JavaScript code attempts to log the type of an undefined variable undef to the console, but throws a ReferenceError instead. When trying to log the result of the expression undef || {"too much": false}, it returns the object literal {"too much": false} to the console due to the undefined value of undef.