es6 ...arg

传n个参

var myfn = function(...arg){
    console.log(arg)
}
myfn(1,2,3,4,5) // [1, 2, 3, 4, 5]

拆开数组传

var myfn = function(x,y,z){
    console.log(x,y,z)
}
var arg = [10,12,34]
myfn(...arg)//(10, 12, 34)

push数组

var arr1 = [2]
var arr2 = [2, 3, 4]
arr1.push(...arr2)
console.log(arr1)//[2, 2, 3, 4]