Object.assign2 = function(target, ...source) {
  let ret = Object(target) 
  source.forEach(function(obj) {
    if (obj) {
      for (let key in obj) {
        if (obj.hasOwnProperty(key)) {
          ret[key] = obj[key]
        }
      }
    }
  })
  return ret
}
const obj1 = {a: 1}
const obj2 = {b: 2}
const res = Object.assign2(obj1, obj2)
console.log(obj1);