AS3 Logical OR

gistfile1.as

// In AS3

a ||= value;

// is shorthand for:

if (a == false) { // 1: Tests truthiness, not strict null
  a = value;
} else {
  a = a; // 2: Will reassign
}

// 2 is important to understand as it impacts setters with side-effects (obviously not a good idea, but still).
// It's a pity that it works this way. Many other languages actually short-circuit - which is much more desirable.