javascript - 计算递归函数中变量的结果

Question

我已经编写了打印楼梯算法。给定 n 的函数打印楼梯 n 级。

    var i = 1;
    function printStaircase(n) {
      //Base case
      if (n < 1) return n;
      //Recursive case
      var line = '';
      line += ' '.repeat(n - 1);
      line += '*'.repeat(i);
      console.log(line);
      i++;
      return printStaircase(n - 1);
    }
    
    printStaircase(10);

如您所见，我必须从外部传入 i 变量。我想知道如何在函数体内计算 i 的值时完成，以便它是独立的并且不会从全局范围内获取任何东西

Answer 1

递归 super 有趣-

const chars = (c = "") => (n = 0) =>
  n === 0
    ? ""
    : c + chars (c) (n - 1)

const spaces =
  chars (" ")

const stars = 
  chars ("*")

const newline =
  "\n"

const stairs = (n, m = n - 1) =>
  m <= 0
    ? ""
    : spaces (m)
      + stars (n - m)
      + newline
      + stairs (n, m - 1)
      
console .log (stairs (10))

console .log (stairs (4))