Why use named function expressions?

Question

We have two different way for doing function expression in JavaScript:

Named function expression (NFE):

var boo = function boo () {         


        

Answer 1

If a function is specified as a Function Expression, it can be given a name.

It will only be available inside the function (except IE8-).

var f = function sayHi(name) {
  alert( sayHi ); // Inside the function you can see the function code
};

alert( sayHi ); // (Error: undefined variable 'sayHi')

This name is intended for a reliable recursive function call, even if it is written to another variable.

In addition, the NFE (Named Function Expression) name CAN be overwritten with the Object.defineProperty(...) method as follows:

var test = function sayHi(name) {
  Object.defineProperty(test, 'name', { value: 'foo', configurable: true });
  alert( test.name ); // foo
};

test();

Note: that with the Function Declaration this can not be done. This "special" internal function name is specified only in the Function Expression syntax.