尾递归和蹦床函数

Sum函数：

const sum = (n) => {
  if (n <= 1) return n;
  return n + sum(n-1)
}

尾递归：

const sum = (n, prevSum = 0) => {
  if (n <= 1) return n + prevSum;
  return sum(n-1, n + prevSum)
}

尾递归+蹦床

const sum0 = (n, prevSum = 0) => {
  if (n <= 1) return n + prevSum;
  return () => sum0(n-1, n + prevSum)//改造1. 返回函数闭包，创造新匿名函数并创造新的sum0，
  否则会把参数注入到原始u的sum0中
}
const trampoline = f => (...args) => {
  let result = f(...args);
  while (typeof result === 'function') {
    result = result();
  }
  return result;
}
const sum = trampoline(sum0);

console.log(sum(1000000)); // 不会栈溢出

蹦床es5

function trampoline(f) {
  return function trampolined(...args) {
    let result = f.bind(null, ...args);

    while (typeof result === 'function') result = result();

    return result;
  };
}