Nullish coalescing operator (??) vs OR(||)
(raw notes)
Nullish coalescing operator (??)
if the left side operand is NULL or UNDEFINED, the right-hand side operand is returned.
const foo = null ?? 'default string'; console.log(foo); // Expected output: "default string"
Nullish values are : NULL and Undefined
Falsey values, these below are the only falesy values in JS
Some more examples
false ?? "llo" -> since the left hand side operand is not a nullish value -> so the left hand side value is returned
\=> false
false || "llo" -> here the left side value is a falsey value so the right hand side value will be returned
\=>"llo"
| Value | Type | Description |
| null | Null | The keyword null — the absence of any value. |
| undefined | Undefined | undefined — the primitive value. |
false | Boolean | The keyword false. |
| NaN | Number | NaN — not a number. |
0 | Number | The Number zero, also including 0.0, 0x0, etc. |
-0 | Number | The Number negative zero, also including -0.0, -0x0, etc. |
0n | BigInt | The BigInt zero, also including 0x0n, etc. Note that there is no BigInt negative zero — the negation of 0n is 0n. |
"" | String | Empty string value, also including '' and `` . |
document.all | Object | The only falsy object in JavaScript is the built-in document.all. |
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Nullish_coalescing