this ana yanke shi ne ta yaya aka kira aiki, ba inda aka fada shi ba. Akwai ƙaidodi gida biyar:
js
obj = {
: ,
() { .; },
};
obj.();
f = obj.;
();
f.(obj);
();
this ana yanke shi ne ta yaya aka kira aiki, ba inda aka fada shi ba. Akwai ƙaidodi gida biyar:
obj = {
: ,
() { .; },
};
obj.();
f = obj.;
();
f.(obj);
();
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:
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); });
},
};
Mika aiki-yayi azaman kiran bayani yana rasa haɗin sa, saboda a jiya ana kiransa ƙansa:
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
Kanawa nisan this shine ɗaya daga cikin manyan kurakuran JS.
Fasalin shine yawanci aiki-kibiya ko .bind() don kulle this da niyyar.