IIFE 函数是否在调用它的相同函数上下文中执行

Question

Just trying to understand how the IIFE functions executes under the hood in JavaScript engine.

I know every new function has execution context on call stack, but if IIFE function is called in particular function, then will it create new context for the IIFE, or will that be executed in the same context where it is being called?

function myFunction(){
  console.log('inside the myFunction');
  (function(){
      console.log('inside the IIFE')
  })()
}
myFunction();

So how the execution context is created for normal function and IIFE ?

Answer 1

You probably mean "IIFE", or "Immediately Invoked Function Expression".

Yes, IIFEs result in their own execution context. When the IIFE is invoked, it goes onto the call stack, and when the function ends, it gets removed from the call stack, just like with normal named functions. Recursively called IIFEs can result in a stack overflow too, after all:

 (function iife() { iife() })();

Just like named functions, IIFEs may also even have variables which are defined only inside them, and have their own parameters:

 (function (param) { const someOtherVarName = true; })('param'); console.log(typeof param, typeof someOtherVarName);

So, in terms of execution context and variable scoping, there isn't really much difference between an IIFE and the invocation of a named function.