Wace bambanci tsakanin == da === ?

Question

Accepted Answer

**`===`** (daidaitaccen daidaito) yana kwatantawa da kimar **da** nau'i babu juyawa. **`==`** (saurin daidaito) yana aiwatar da **juyawa nau'i** da farko, wanda ke haifar da sakamako mai mamaki.

```js
0 == "0";    // true  — "0" coerced to 0
0 == "";     // true  — "" coerced to 0
0 == false;  // true  — false coerced to 0
null == undefined; // true  — special rule
"" == false; // true

0 === "0";   // false — different types, no coercion
NaN === NaN; // false — NaN is never equal to anything
```

## Me ya sa == yana haɗari

Sararin juyawa ba a fahimta ba kuma yana haifar da kurakurai. Alal misali, `[] == ![]` shine `true` (wata sanuwar shahararren asali). Ba ka da buƙatun JavaScript ya sauya nau'i cikin shiru bayan bayar-bayarwa yayin kwatantawa.

## Doka

**Koyaushe yi amfani da `===`** (da `!==`). Sauran sakamako gida, da gida ne jankali shine binciken null *ko* undefined tare-tare:

```js
if (value == null) { ... } // true for BOTH null and undefined — a deliberate idiom
```

Gare sauran ƙoli, daidaitaccen daidaito yana tsara kwatantawa. Don kwatantawa abubuwa kuna buƙata zurfin-daidaito bincike (suna kwatantawa ta sandar, don haka `{a:1} === {a:1}` shine `false`).