jlin.py

def my_reduce(func, lst):
    #base case
    if (len(lst) == 1):
        return lst[0]
    #recurse
    temp = func(lst[0], lst[1])
    return my_reduce(func, [temp] + lst[2:])
  

myReduce.js

function myReduce(cb, initial, arr) {
	let acc = initial; // would need to clone ref vals
	for (let i = 0, l = arr.length; i < l; i++) {
		if (typeof acc === 'undefined') {
			acc = arr[i];
			continue;
		}
		acc = cb(acc, arr[i]);
	}
	return acc;
}

let a = [1, 2, 3];

let sum = myReduce.bind(null, (acc, cur) => acc + cur, undefined);

console.log(sum(a)); // 6