Apa minangka nilai-nilai truthy lan falsy?

Question

Accepted Answer

Ing konteks boolean (a `if`, `&&`, `||`, `!`), saben nilai dirawat minangka **truthy** utawa **falsy**. Ana tekan **8 nilai falsy** — kabeh liyane yaiku truthy.

Nilai-nilai falsy: `false`, `0`, `-0`, `0n` (BigInt zero), `""` (empty string), `null`, `undefined`, `NaN`.

```js
if ("")    {} // skipped — empty string is falsy
if (0)     {} // skipped
if ("0")   {} // RUNS — non-empty string is truthy!
if ([])    {} // RUNS — empty array is truthy!
if ({})    {} // RUNS — empty object is truthy!
```

Paningalan: `"0"`, `[]`, lan `{}` kabeh **truthy**, sanajan padamaranmu "kosong."

## Bug sing umum lan nyata

```js
const name = input || "guest"; // ❌ if input is "" or 0, falls back to "guest"
const count = input ?? 0;       // ✅ ?? only falls back on null/undefined
```

`||` mundur kanggo **saben** nilai falsy, dadi valid `0` utawa `""` dikamesthoni. Operator **nullish coalescing** `??` mundur **mung** kanggo `null`/`undefined`, sing biasane sing benere diperlokake.

## Apa dadi penting

Ngerti set falsy sing tepat nyegah bug-bug sumurup — khusushin njaga angka (`if (count > 0)` ora `if (count)`) lan milih `??` vs `||` kanggo defaults.