实现长度为 m 的字符串 a 到长度为 n 的字符串 b 的遍历

str_gen.js

function* gen(min, max) {
    var arr = new Array(min).fill(0)
    arr[arr.length - 1] = 1
    while (arr.length <= max) {
        yield arr.map(x => String.fromCharCode(96 + x)).join('')
        arr[arr.length - 1]++
        for (var i = arr.length - 1; i >= 0; i--) {
            if (arr[i] > 26) {
                arr[i] -= 26
                if (i == 0) {
                    arr.unshift(1)
                } else {
                    arr[i - 1] += 1
                }
            }
        }
    }
}

// useage

var g = gen(1,2)
while (true) {
    var d = g.next()
    if (d.done) {
        break
    }
    console.log(d.value)
}