lodash内部方法getData和setData实例解析

import WeakMap from './_WeakMap.js';
var metaMap = WeakMap && new WeakMap;

import getNative from './_getNative.js';
import root from './_root.js';
var WeakMap = getNative(root, 'WeakMap');

function noop() {}

import metaMap from './_metaMap.js';
import noop from './noop.js';
var getData = !metaMap ? noop : function(func) {
  return metaMap.get(func);
};

import identity from './identity.js';
import metaMap from './_metaMap.js';
var baseSetData = !metaMap ? identity : function(func, data) {
  metaMap.set(func, data);
  return func;
};

var HOT_COUNT = 800,
    HOT_SPAN = 16;
function shortOut(func) {
  var count = 0,
      lastCalled = 0;
  return function() {
    var stamp = nativeNow(),
        remaining = HOT_SPAN - (stamp - lastCalled);
    lastCalled = stamp;
    if (remaining > 0) {
      if (++count >= HOT_COUNT) {
        return arguments[0];
      }
    } else {
      count = 0;
    }
    return func.apply(undefined, arguments);
  };
}

import baseSetData from './_baseSetData.js';
import shortOut from './_shortOut.js';
var setData = shortOut(baseSetData);