Execution context and call stack?

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🤯 Under the hood of the JavaScript series! 3️⃣ Execution context and call stack? A Thread🧵👇

🤔 A real-world scenario of the execution context. → Suppose, the execution context is like the "stadium" of the game, where players can play the game. → So just like this, there is also a "stadium" in JavaScript where all code will be executed.

→ This "stadium" is known as the 𝗚𝗹𝗼𝗯𝗮𝗹 𝗘𝘅𝗲𝗰𝘂𝘁𝗶𝗼𝗻 𝗖𝗼𝗻𝘁𝗲𝘅𝘁 in JavaScript. → As we already know that a game can be played in one stadium at a time, similarly JavaScript has only one 𝗚𝗹𝗼𝗯𝗮𝗹 𝗘𝘅𝗲𝗰𝘂𝘁𝗶𝗼𝗻 𝗖𝗼𝗻𝘁𝗲𝘅𝘁 (GEC) in a JS file.

📌 What is 𝗚𝗹𝗼𝗯𝗮𝗹 𝗘𝘅𝗲𝗰𝘂𝘁𝗶𝗼𝗻 𝗖𝗼𝗻𝘁𝗲𝘅𝘁? → After the compilation of JavaScipt code, a global execution context will be created. → Global Execution Context is the default place where all global JavaScript code (which is not inside a function) gets executed.

→ Or, a global execution context will be created for the top-level code, which is not inside a function. → And when we call a function then there is a new execution context will be created inside the Global Execution Context.

→ There can be more than one execution context placed inside the Global Execution Context. → Simple, when we call a function then there is a new execution context that will be created inside the Global Execution Context every time.

→ A Global Execution Context can contain global let, const, var declaration, function, scope chain, etc. → Remember, there can be more than one execution context inside the Global Execution Context. → So all these execution contexts make up together a 𝗰𝗮𝗹𝗹 𝘀𝘁𝗮𝗰𝗸.

📌 What is a 𝗰𝗮𝗹𝗹 𝘀𝘁𝗮𝗰𝗸? → A call stack is the combination of a Global Execution Context as well as more than one execution context that is kept inside a function. → All execution contexts will be stacked on top of each other.

→ When the Global Execution Context will be created it will be stored in a call stack just like in the above picture. → And when we call a function then the new execution context will be created after completing the job it will remove from the call stack. ⛔ Just like LIFO

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