mout/object/reduce.js

var forOwn = require('./forOwn');
var size = require('./size');

    /**
     * Object reduce
     */
    function reduce(obj, callback, memo, thisObj) {
        var initial = arguments.length > 2;

        if (!size(obj) && !initial) {
            throw new Error('reduce of empty object with no initial value');
        }

        forOwn(obj, function(value, key, list) {
            if (!initial) {
                memo = value;
                initial = true;
            }
            else {
                memo = callback.call(thisObj, memo, value, key, list);
            }
        });

        return memo;
    }

    module.exports = reduce;