把一个数组分成每一份只有n个

举个栗子

let list = ['a','b','c','d','e']
// 想把arr变成这样: [['a','b'],['c','d'],['e']]
let arr = []
for(let i = 0, length = list.length; i < length; i += 2){
    arr.push(list.slice( i,i + 2 ))
}
console.log(arr)