arr=[1,2,3]
arr1=[4,5,6]
arr3=[...arr,...arr1]
console.log(arr3)
console.log(arr.concat(arr1))
const target = { a: 1 };
const source1 = { b: 2 };
const source2 = { c: 3 };
obj =Object.assign(target, source1, source2)
console.log(obj)
console.log(Object.prototype.toString.call(obj))