Javascript function. Don't understand how function inside self-function work -

would ask javascript function.

i don't understand below function, thought @ line 4 fib(n-1) return 1 , latter fib(n-2) return 0, , both add 1.

may know why final result f(10); 55, can't head around this.

anyone can explain me happening behind scene, please?

thanks! ;)

var f = function fib(n) {     if (n === 0) return 0;     if (n === 1) return 1;     if (n > 1) return fib(n - 1) + fib(n - 2);      // *2 }; f(10);       // 55 

ref: https://slides.com/concise/js/fullscreen#/35

like this. typical recursive function, 2 base cases , 1 recursive step.

remember if n 10, fib(n - 1) fib(9), , on:

fib(10) = fib(9) + fib(8) = 34 + 21 = 55 fib(9)  = fib(8) + fib(7) = 21 + 13 = 34 fib(8)  = fib(7) + fib(6) = 13 +  8 = 21 fib(7)  = fib(6) + fib(5) =  8 +  5 = 13 fib(6)  = fib(5) + fib(4) =  5 +  3 =  8 fib(5)  = fib(4) + fib(3) =  3 +  2 =  5 fib(4)  = fib(3) + fib(2) =  2 +  1 =  3 fib(3)  = fib(2) + fib(1) =  1 +  1 =  2 fib(2)  = fib(1) + fib(0) =  1 +  0 =  1 fib(1)  =                              1 fib(0)  =                              0 

side note: although example illustration of recursive functions, it's extremely inefficient way calculate fibonacci numbers. better approach use memoization eliminate bulk of inefficiency:

var fib = (function () {    var cache = [0, 1];        return function fib(num) {      if (!(num in cache)) {           cache[num] = fib(num - 1) + fib(num - 2);      }      return cache[num];    };  })();    console.log(fib(10));

http://jsperf.com/fibonacci-memoization-2015-04-01