Check exactly one boolean option set

Question

Well, this is kind of hacky:

function b2n(boo) {
    return boo ? 1 : 0;
}

if(b2n(opt1) + b2n(opt2) + b2n(opt3) !== 1) {
    throw new Error(\"Exactly one o         


        

Answer 1

if ([opt1, opt2, opt3].reduce(function(x, y) { return x + !!y }, 0) == 1) {
    // exactly one
};

ECMAScript 5 reduce function.