Why does `1 && true` get a bool value `true`, but `0 && true` get a number `0`?

Question

Why does 1 && true get a bool value true, but 0 && true get a number 0? I tested it in Chrome Console and Firebug.

Answer 1

Because expr1 && expr2 will return expr1 if it is false, otherwise it will return expr2.

Answer 2

Because that is how logical operators in Javascript are defined to behave.

Additional reference: ECMA 262, page 83.

Answer 3

The && operator is commonly called logical and. If the first operand is false, null, undefined, "" or the number 0 then it returns the first operand. Otherwise, it returns the second operand