es6 ...展开运算符

let a = {aa:'aa'}
let b = {bb:'bb'}
let c = {...a,...b}
console.log(c)
// {"aa":"aa","bb":"bb"}

2.

let d = ['dd']
let e = ['ee']
let f = [...d,...e]
console.log(f)
// ["dd","ee"]

3.

let g = [{gg:'gg'}]
let h = {hh:'hh'}
let i = [...g,h]
console.log(i)
// [{"gg":"gg"},{"hh":"hh"}

4.数组+字符串

let j = ['jj']
let k = 'kk'
let l = [...j,k]
console.log(l)
// ["jj","kk"]