𝗝𝗮𝘃𝗮𝗦𝗰𝗿𝗶𝗽𝘁 𝗦𝗰𝗼𝗽𝗲: 𝗕𝗹𝗼𝗰𝗸, 𝗚𝗹𝗼𝗯𝗮𝗹, 𝗮𝗻𝗱 𝗙𝘂𝗻𝗰𝘁𝗶𝗼𝗻

𝗝𝗮𝘃𝗮𝗦𝗰𝗿𝗶𝗽𝘁 𝗦𝗰𝗼𝗽𝗲: 𝗕𝗹𝗼𝗰𝗸, 𝗚𝗹𝗼𝗯𝗮𝗹, 𝗮𝗻𝗱 𝗙𝘂𝗻𝗰𝘁𝗶𝗼𝗻

Scope huamua wapi unatumia variable katika kodi yako.

1. Global Scope Variable huishi nje ya function au block. Unaweza kuzipata kutoka mahali popote katika script yako. Onyo: Global variables husababisha hitilafu (bugs) kwa sababu sehemu yoyote ya kodi yako inaweza kuzibadilisha.

2. Function Scope Variable huishi ndani ya function. Unaweza kuzipata ndani tu ya function hiyo mahususi.

3. Block Scope Hii inahusu JavaScript ya kisasa inayotumia let au const. Variable huishi ndani ya mabano ya mraba {}. Block inajumuisha:

• kauli za if
• mzunguko wa for
• mzunguko wa while
• block zinazojitegemea {}

Muhtasari wa Scope:

• Global: Inapatikana kila mahali.
• Function: Inapatikana ndani tu ya function.
• Block: Inapatikana ndani tu ya mabano ya mraba {}.
• var: Inatumia function scope. Haizingatii block scope.
• let na const: Zinatumia block scope. Tumia hizi kwa kodi bora zaidi.

Kuelewa Processes na Threads

Process ni programu inayojiendesha ikiwa na kumbukumbu (memory) yake yenyewe. Fikiria WhatsApp kama process.

Thread ni sehemu ndogo ya process. Threads hushiriki kumbukumbu (memory) ile ile.

• Threads ni nyepesi (lightweight).
• Ni haraka kuzitengeneza.
• Zinakuwezesha kufanya mambo mengi kwa wakati mmoja.

Mfano wa WhatsApp: Process moja (WhatsApp) huendesha threads nyingi:

• Kupokea ujumbe
• Kutuma picha
• Kucheza video
• Kuonyesha arifa (notifications)

Chanzo: https://freeacademy.ai/lessons/global-vs-function-vs-block-scope Chanzo: https://josephcardillo.medium.com/the-difference-between-function-and-block-scope-in-javascript-4296b2322abe