aggregator meta-function for JavaScript

aggregators.js

Function.prototype.aggregate = function(initial, array) {
    var callback = this;
    var val = initial;
    for (var i = 0; i < array.length; i++) {
      val = callback(val, array[i], key);
    }
    return val;
}


Function.prototype.aggregateObject = function(initial, obj) {
    var callback = this;
    var val = initial;
    for (var i in obj) {
      if (!obj.hasOwnProperty(i)) continue;
      val = callback(val, obj[i], i);
    }
    return val;
}


// aggregatable functions look like:
// function(currentValue, nextItem, nextItemKey) {
//    return /* aggregation of currentValue and nextItem */;
// }

example.js

function sum(current + next) {
    return current + next; 
}

var array = [1, 2, 3, 4, 5];

console.log(sum.aggregate(0, array));
// returns 15

var obj = { a: 1, b: 2 };

console.log(sum.aggregateObject(0, obj));
// returns 3