// 大整形       // let n = 521n;       // console.log(n,typeof(n));
      // 函数       // let n = 123;       // console.log(BigInt(n));

      // 大数值 运算       let max = Number.MAX_SAFE_INTEGER;       console.log(max); // 9007199254740991       console.log(max + 1); // 9007199254740992       console.log(max + 2); // 9007199254740992
      console.log(BigInt(max)); // 9007199254740991n       console.log(BigInt(max) + BigInt(1)); // 9007199254740992n       console.log(BigInt(max) + BigInt(2)); // 9007199254740993n