dewedev/node_modules/underscore/modules/each.js

import optimizeCb from './_optimizeCb.js';
import isArrayLike from './_isArrayLike.js';
import keys from './keys.js';

// The cornerstone for collection functions, an `each`
// implementation, aka `forEach`.
// Handles raw objects in addition to array-likes. Treats all
// sparse array-likes as if they were dense.
export default function each(obj, iteratee, context) {
  iteratee = optimizeCb(iteratee, context);
  var i, length;
  if (isArrayLike(obj)) {
    for (i = 0, length = obj.length; i < length; i++) {
      iteratee(obj[i], i, obj);
    }
  } else {
    var _keys = keys(obj);
    for (i = 0, length = _keys.length; i < length; i++) {
      iteratee(obj[_keys[i]], _keys[i], obj);
    }
  }
  return obj;
}