[polyfill object assign] #polyfill

object-assign.js

if (typeof Object.assign !== 'function') {
  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 (Object.prototype.hasOwnProperty.call(source, key)) {
            target[key] = source[key]
          }
        }
      }
    }
    return target
  }
}