what the heck is this operator ?? in javascript.

In JavaScript, || (logical OR) and ?? (nullish coalescing) are both used to provide a fallback value, but they work differently:

|| (Logical OR)

• Usage: Used to check if the first value is "falsy" (e.g., false, 0, null, undefined, NaN, "").
• Behavior: Returns the first "truthy" value or the last "falsy" value if none are truthy.

• Example:

  const result = value1 || value2; 
  // If `value1` is "falsy" (like `null`, `0`, `""`), `value2` will be returned.

?? (Nullish Coalescing)

• Usage: Used to check specifically if a value is null or undefined.
• Behavior: Returns the right-hand value only if the left-hand value is null or undefined.

• Example:

  const result = value1 ?? value2;
  // If `value1` is `null` or `undefined`, `value2` will be returned.

Key Difference

• || checks for "falsy" values (like 0, false, "", null, undefined), whereas ?? only checks for null or undefined.

When to Use Which

• Use || when you want to provide a default value for any "falsy" condition.
• Use ?? when you want to differentiate between null/undefined and other "falsy" values like 0 or an empty string ("").