𝗢𝗯𝗷𝗲𝗰𝘁𝘀 katika JavaScript
Objects za JavaScript huhifadhi data katika jozi za funguo-na-thamani (key-value pairs). Kila jozi huitwa sifa (property).
Funguo (key) ni string. Thamani (value) inaweza kuwa kitu chochote. Inaweza kuwa string, namba, array, au function.
Creating Objects
Unatumia njia ya object literal notation kutengeneza object. Tumia mabano ya kote {} kuifafanua.
Object tupu:
let empty = {};
Object yenye sifa:
let person = { firstName: 'John', lastName: 'Doe' };
Accessing Properties
Unatumia njia mbili kupata data kutoka kwenye object.
Dot notation Tumia nukta ikifuatiwa na jina la sifa.
person.firstNameArray-like notation Tumia mabano ya mraba
[]na alama za nukuu. Hii ni lazima ikiwa jina la sifa yako lina nafasi (spaces).person['firstName']
Mfano wenye nafasi:
let address = { 'building no': 3960 };
address['building no']
Note: Epuka kutumia nafasi katika majina ya sifa ili kuzuia makosa.
Managing Properties
Unaweza kubadilisha, kuongeza, au kufuta data wakati wowote.
Kubadilisha thamani:
person.firstName = 'Jane';
Kuongeza sifa mpya:
person.age = 25;
Kufuta sifa:
delete person.age;
Ukijaribu kupata sifa ambayo haipo, JavaScript hurudisha undefined.
Check if a property exists
Tumia opereta ya in kuangalia funguo. Inarudisha true au false.
'employeeId' in employee
Hii inakuambia ikiwa funguo hiyo ipo ndani ya object.