[removed] Conditional (ternary) vs boolean OR for non-boolean values?

Question

In JavaScript, can I always use boolean OR instead of conditional operator for all kind of variables (e.g. string, function, ...)?

For example z = (x || y)

Answer 1

They are similar, but are not quite the same. x ? x : y ends up evaluating x twice if x is chosen. This could cause an unexpected effect if x is a function call.

You can find a formal proof of this in the ECMA specification.

Another way to prove this:

function a() { c++; return true; }
function b() { d++; return true; }
var c = 0, d = 0;
a() || 3;
b() ? b() : 3;
/* c is 1; d is 2 */