https://bigfrontend.dev/zh/problem/implement-Object.is

    1. function is(a, b) {
    2.   if (a === b) {
    3.     return a !== 0 || 1 / a === 1 / b;
    4.   }
    5.   return a !== a && b !== b;
    6. }

    https://leetcode-cn.com/problems/decode-string/

    function decodeString(s: string): string {
  let result = '';
  let prevNum = 0;
  const numStack: number[] = [];
  const strStack: string[] = [];
  for (const char of s) {
    const c = Number.parseInt(char);
    if (Number.isInteger(c)) {
      prevNum = prevNum * 10 + c;
    } else if (char === '[') {
      numStack.push(prevNum);
      strStack.push(result);
      result = '';
      prevNum = 0;
    } else if (char === ']') {
      const repeatTimes = numStack.pop();
      result = strStack.pop() + result.repeat(repeatTimes);
    } else {
      result += char;
    }
  }
  return result;
};