logicalAssignmentOperators.md

[JavaScript] - Logical Assignment Operators

||=, &&=, ??=

const rest1 = {
  name: 'Capri',
  numGuests: 20,
};

const rest2 = {
  name: 'La Piazza',
  owner: 'Giovanni Rossi',
};

OR assignment operator

// instead of this
// rest1.numGuests = rest1.numGuests || 10;
// rest2.numGuests = rest2.numGuests || 10;

// we can do this
rest1.numGuests ||= 10;
rest2.numGuests ||= 10;

console.log(rest1, rest2);

Nullish assignment operator

const rest3 = {
  name: 'Mexica',
  numGuests: 0,
};

// this one doesn't work, it will returns 10
// rest3.numGuests ||= 10;

// use this instead
rest3.numGuests ??= 10; // this will return the expected 0

console.log(rest3);

AND assignment operator

// rest1.owner is undefined (the first falsy value) so it will get assigned to rest1.owner
//rest1.owner = rest1.owner && '<ANONYMOUS>'; // rest1.owner is now undefined
// both rest2.owner and 'ANONYMOUS' is truthy so the last value will be assigned to rest2.owner
//rest2.owner = rest2.owner && '<ANONYMOUS>'; // rest2.owner is now '<ANONYMOUS>'

rest1.owner &&= 'ANONYMOUS'; // owner = undefined now is not set to rest1 anymore
rest2.owner &&= 'ANONYMOUS';

console.log(rest1, rest2);