Yaya aka sanyi `this` ya zama?

Question

IT Interview Practice · Accepted Answer

`this` ana yanke shi ne **ta yaya aka kira aiki, ba inda aka fada shi ba**. Akwai ƙaidodi gida biyar:

```js
const obj = {
  x: 1,
  getX() { return this.x; },
};

obj.getX();          // 1   → method call: `this` is `obj`
const f = obj.getX;
f();                  // undefined (or window) → plain call: `this` is global/undefined
f.call(obj);          // 1   → explicit binding with call/apply/bind
new SomeClass();      //     → `this` is the brand-new instance
```

## Canji na aiki-kibiya (wannan mahimmaci)

Aikina kibiya ba su da **kansu `this`** — suna karɓa shi daga ƙunshi ƙadarorin a lokacin bayyana. Ga wannan dalili kibiyoyi suke da kyau don kiran bayanai:

```js
const obj = {
  items: [1, 2],
  logAll() {
    // ✅ arrow inherits `this` from logAll → `this` is obj
    this.items.forEach(i => console.log(this.items, i));

// ❌ a regular function here would have its own `this` (undefined) → crash
    // this.items.forEach(function (i) { console.log(this.items); });
  },
};
```

## Ƙabon da aka sani

Mika aiki-yayi azaman kiran bayani **yana rasa** haɗin sa, saboda a jiya ana kiransa ƙansa:

```js
button.addEventListener("click", obj.getX);        // ❌ `this` is the button
button.addEventListener("click", () => obj.getX()); // ✅ keeps obj
button.addEventListener("click", obj.getX.bind(obj)); // ✅ also fine
```

## Me ya sa yake da muhimma

Kanawa nisan `this` shine ɗaya daga cikin manyan kurakuran JS.

Fasalin shine yawanci aiki-kibiya ko `.bind()` don kulle `this` da niyyar.

Canji na aiki-kibiya (wannan mahimmaci)

Ƙabon da aka sani

Me ya sa yake da muhimma

Tambayoyi masu alaƙa