JavaScript: || and ?? Are Not the Same

In JavaScript, the logical operators || (logical OR) and ?? (nullish coalescing operator) may seem similar at first glance, but they have important differences in their behavior and usage.

The || operator returns the first truthy operand, or the last operand if all operands are falsy. This means that if any of the operands in an || expression evaluates to a truthy value, the entire expression will return that value. For example:

const x = 5 || 0;
console.log(x); // Output: 5

const y = false || "hello";
console.log(y); // Output: "hello"

In the first example, the expression 5 || 0 returns 5 because 5 is a truthy value. In the second example, the expression false || "hello" returns "hello" because "hello" is the first truthy value encountered in the expression.

The ?? operator, on the other hand, returns the first operand that is not null or undefined, or the last operand if all operands are null or undefined. This means that if any of the operands in a ?? expression evaluates to a non-nullish value, the entire expression will return that value. For example:

const x = null ?? 5;
console.log(x); // Output: 5

const y = undefined ?? "hello";
console.log(y); // Output: "hello"

In the first example, the expression null ?? 5 returns 5 because 5 is the first…