Cartesian product 笛卡尔积 with Javascript

No Recursive 非递归

var test = [[1,2],[3,4,5],[7,8]]
var result = []
var count = 1

for (var i = 0 ; i < test.length ; i ++) {
    count *= test[i].length
}
for (var i = 0 ; i < count ; i ++) {
    result.push([])
}

var loopLength = count
for (var i = 0 ; i < test.length ; i ++) {
    var loopUnit = loopLength / test[i].length
    for (var j = 0 ; j < count ; j ++) {
        var sit = parseInt(j / loopUnit) % test[i].length
        result[j].push(test[i][sit])
    }
    loopLength = loopUnit
}

console.log(result)

Recursive 递归

var test = [[1,2],[3,4,5],[7,8]]
function generate(position, pre) {
    if (position >= test.length) {
        console.log(pre.join(','))
        return
    }
    for (var i = 0 ; i < test[position].length ; i ++) {
        generate(position + 1, pre.concat([test[position][i]]))
    }
}
generate(0, [])