検索するとreduceを使った実装が出てくるので、forEachで処理したい場合のメモ。

code

function chunk(list: Array<number>, count: number): Array<Array<number>> {
    if (count === 0) {
        return [list]
    }
    let res = new Array<Array<number>>()
    let tmp = new Array<number>()
    list.forEach((n, index) => {
        tmp.push(n)
        if ((index + 1) % count === 0) {
            res.push(tmp)
            tmp = []
        }
    })
    if (tmp.length > 0) {
        res.push(tmp)
    }
    return res
}

console.log(0, chunk( [1,2,3,4,5,6,7,8,9,10], 0))
console.log(1, chunk( [1,2,3,4,5,6,7,8,9,10], 1))
console.log(2, chunk( [1,2,3,4,5,6,7,8,9,10], 2))
console.log(3, chunk( [1,2,3,4,5,6,7,8,9,10], 3))
console.log(4, chunk( [1,2,3,4,5,6,7,8,9,10], 4))
console.log(5, chunk( [1,2,3,4,5,6,7,8,9,10], 5))
console.log(6, chunk( [1,2,3,4,5,6,7,8,9,10], 6))
console.log(7, chunk( [1,2,3,4,5,6,7,8,9,10], 7))
console.log(8, chunk( [1,2,3,4,5,6,7,8,9,10], 8))
console.log(9, chunk( [1,2,3,4,5,6,7,8,9,10], 9))
console.log(10, chunk( [1,2,3,4,5,6,7,8,9,10], 10))
console.log(11, chunk( [1,2,3,4,5,6,7,8,9,10], 11))

result

[LOG]: 0,  [[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]] 
[LOG]: 1,  [[1], [2], [3], [4], [5], [6], [7], [8], [9], [10]] 
[LOG]: 2,  [[1, 2], [3, 4], [5, 6], [7, 8], [9, 10]] 
[LOG]: 3,  [[1, 2, 3], [4, 5, 6], [7, 8, 9], [10]] 
[LOG]: 4,  [[1, 2, 3, 4], [5, 6, 7, 8], [9, 10]] 
[LOG]: 5,  [[1, 2, 3, 4, 5], [6, 7, 8, 9, 10]] 
[LOG]: 6,  [[1, 2, 3, 4, 5, 6], [7, 8, 9, 10]] 
[LOG]: 7,  [[1, 2, 3, 4, 5, 6, 7], [8, 9, 10]] 
[LOG]: 8,  [[1, 2, 3, 4, 5, 6, 7, 8], [9, 10]] 
[LOG]: 9,  [[1, 2, 3, 4, 5, 6, 7, 8, 9], [10]] 
[LOG]: 10,  [[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]] 
[LOG]: 11,  [[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]]

on playgound