IE兼容性处理

Object.js

// Object.assign for IE11
if(!Object.assign) {
  Object.assign = function(target) {
    'use strict';
    if(target == null) {
      throw new TypeError('Cannot convert undefined or null to object');
    }

    target = Object(target);
    for(var index = 1; index < arguments.length; index++) {
      var source = arguments[index];
      if(source != null) {
        for (var key in source) {
          if (source.hasOwnProperty.call(source, key)) {
            target[key] = source[key];
          }
        }
      }
    }
    return target;
  }
}