recursion - javascript recursive function memory leak

Question

I am not good at English. Successfully make recursive call function. However, there is a memory leak for some reason. The question is that there is no return. The purpose of this feature is to view and explore objects, arrays, and the rest of their properties. How do I change the code if I have a problem with my return? Thank you in advance.

I was able to know the cause of the memory leak through Google dev tools profiles.

function recursionProperty(prop, obj, fn) {
  if (Array.isArray(obj)) {
    obj.forEach(item => recursionProperty('files', item, fn));
  } else if (obj instanceof Object) {
    Object.keys(obj).forEach(prop => {
      const value = obj[prop];
      recursionProperty(prop, value, fn);
    });
  } else {
    fn(prop, obj);
  }
}

recursionProperty(null, {foo:'bar', baz: ['x','y']}, (prop, obj) => console.log(prop, obj));

Answer 1

There is most likely no memory leak in your code. Yes, recursive functions can be more memory aggressive than normal functions, because the call stack can grow very quickly, but remember that all functions will implicitly return even if there is no return statement. (Imagine that there is always a return undefined; line at the end of all your functions)

When doing a recursion, call stack will grow until you reach the bottom of a recursion branch (no function returns until then). Once the recursion branch end is reached, in your case this happens anytime you reach your else block, call stack will 'collapse' and all functions preceding will 'return'.

Memory will ultimately be freed by garbage collection as required.