JavaScript tell which condition was hit

Question

If I have a statement in JavaScript like:

if(!me.a || !me.b || !me.c) {
     // I want to know which not was matched here
}

How do I know which

Answer 1

Well, one way is to && an identifier with each condition and check the result.

var result = (!me.a && 1) || (!me.b && 2) || (!me.c && 3);

if(result) {
    // if result is 1, then !me.a is true
    // if result is 2, then !me.b is true and !me.a is false
    // if result is 3, only !me.c is true
}