Basic recursion method

multi_by_10.js

function multiBy10(n) {
  // Setup a base return
  if (n <= 1)
    return 10
  // Loop recursive here
  else
    return 10 + multiBy10(n-1)
}

/**
* multiBy10(3) = (10 + multiBy(2))
*              = (10 + (10 + multiBy(1)))
*              = (10 + (10 + (10)))
*              = 30
**/

tail_calls.js

// Reference from http://www.datchley.name/recursion-tail-calls-and-trampolines/

// Generate an array of integers in the range s -> e.
// Iterative implementation
function range(s, e) {  
    var res = [];

    while (s != e) {
        res.push(s);
        s < e ? s++ : s--;
    }
    res.push(s); 
    return res;
}

range(1,4);  // [1,2,3,4]  
range(-5,1); // [-5,-4,-3,-2,-1,0,1] 

// Generate an array of numbers in a given range.
// Recursive implementation
function range(s, e) {  
  var res = [];

  res.push(s);
  return s == e ? res : res.concat(range(s<e ? ++s : --s, e));
}

range(1,4); // [1,2,3,4]  

/**
* if we return the results of a function call (recursive or not) 
* at the end of our function and none of our function's local environment 
* is needed as part of that evaluation, then that function call is said 
* to be in tail position
**/
// Generate an array of numbers in a given range.
// Tail Recursive implementation
function range(s, e, res) {  
  res = res || [];
  res.push(s);
  return s == e ? res : range(s<e ? ++s : --s, e, res);
}

range(1,4); // [1,2,3,4]