&& es || operatorok javascriptben

Crockford video (28:20)

&& operator

• The guard operator, aka logical and

• If first operand is truthy
  then result is second operand
  else result is first operand

• It can be used to avoid null references
  if (a) {
return a.member;
} else {
return a;
}

• can be written as
  return a && a.member;

|| operator

• The default operator, aka logical or

• If first operand is truthy
  then result is first operand
  else result is second operand

• It can be used to fill in default values.
  var last = input || nr_items;

• (If input is truthy, then last is input, otherwise set last to nr_items.)