Can you write nested functions in JavaScript?

javascript function nested
Red Swan picture Red Swan · Jul 9, 2010 · Viewed 166.7k times · Source

I am wondering if JavaScript supports writing a function within another function, or nested functions (I read it in a blog). Is this really possible?. In fact, I have used these but am unsure of this concept. I am really unclear on this -- please help!

Answer

kennytm picture kennytm · Jul 9, 2010

Is this really possible.

Yes.

function a(x) {    // <-- function
  function b(y) { // <-- inner function
    return x + y; // <-- use variables from outer scope
  }
  return b;       // <-- you can even return a function.
}
console.log(a(3)(4));

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