Do the && and || operators convert their operands to booleans?

Question

Flanagan\'s O\'Reilly JavaScript book states:

Unlike the && and || operators, the ! operator converts its operand to a boolean value [...] b

Answer 1

They do convert the values to boolean, but only to determine how to proceed in evaluating the expression. The result of the expression is not necessarily boolean (in fact, if neither of your operands are boolean, it will not give you a boolean):

var x = false || 'Hello' // gives you 'Hello'
var y = 0 && 1           // gives you 0, because 0 is "falsy" and short circuits
var z = 1 || 2           // gives you 1, because 1 is "truthy" and short circuits