Miscellaneous Operators

Suppose a user sets the volume of a media player to 0, and the program fills in a default of 50 when no volume is set. Two operators that look alike give different answers here:

const volume = 0;
console.log(volume || 50);
console.log(volume ?? 50);

50
0

The first line ignores the user's choice, and the second keeps it. The two operators replace different sets of left operands, and 0 is in only one of those sets