Call stack

• A call stack is a mechanism for an interpreter (like the JavaScript interpreter in a web browser) to keep track of its place in a script that calls multiple functions — what function is currently being run and what functions are called from within that function, etc.

• In summary, then, we start with an empty Call Stack. Whenever we invoke a function, it is automatically added to the Call Stack. Once the function has executed all of its code, it is automatically removed from the Call Stack. Ultimately, the Stack is empty again.

• Example: function greeting() { // [1] Some code here sayHi(); // [2] Some code here } function sayHi() { return “Hi!”; }

// Invoke the greeting function greeting();

// [3] Some code here

• resource: https://developer.mozilla.org/en-US/docs/Glossary/Call_stack

The JavaScript Call Stack

• call stack is synchronous; single threaded
• this is why It is important to understand Call Stack when adopting Asynchronous

How does it work?

• A function invocation creates a stack frame that occupies a temporary memory.

• It works as a LIFO — Last In, First Out data structure.