Recursive __javascript of JS function

This blog mainly tells about the function of JS recursive, mainly from the "variable + function" and "function + variable" Two aspects explained.
Relatively simple, directly on the code.

I. Knowledge Description

function Fun ()
{
    //self calls itself, called recursive call
    fun ();
    Console.log ("M2");
}
Fun ();

Second, function + variable

Use recursive return for 5 factorial
//n! = n * (n-1)!

Defines a function that is used to find the factorial function of n
func (n)
{
    if (n = 1)
    {return
        1;
    }

    Func (n-1) because the parameters passed are n-1, then the factorial return
    N * func (n-1) is asked (n-1);
Console.log (     func (5)   );

function + function

The question of Netherfield (Rabbit Polaci)--a pair of rabbits are born every month from the 3rd month after birth, rabbit long to the third month after a pair of rabbits each month, if the rabbit does not die, ask the number of rabbits per month
//yield analysis: 1, 1, 2, 3, 5, 8, 13, 21 ... The total number of rabbits per month = number of rabbits in the month of N-1 + the total number of rabbits in  n-2 months
//problem: Find the total number of rabbits in any month

function func (n)
{
    if ( n = = 0 | | n = = 1)
    {return
        1;
    }
    return func (n-1) + func (n-2);
}

var a = func ();
Console.log (a);

In a way, the recursion of a function is to call itself in a function . The concept is the case, it depends on how flexible you call.