bbo/reduce.js

bbo is a utility library of zero dependencies for javascript.

'use strict';

/* eslint-disable no-param-reassign */

/* eslint-disable max-params */
function reduce(obj, predicate
/* , initialValue */
) {
  var args = [callback];
  var hasInitialValue = (2 in arguments);
  hasInitialValue && args.push(arguments[2]);

  function callback(previousValue, currentKey, currentIndex, array) {
    if (!hasInitialValue) {
      previousValue = obj[array[0]];
      hasInitialValue = true;
    }

    return predicate(previousValue, currentKey, obj[currentKey], currentIndex, array);
  }

  return Array.prototype.reduce.apply(Object.keys(obj), args);
}

module.exports = reduce;