JavaScript

Mister-Hope

/**
 * Runtime: 84 ms, faster than 97.73% of JavaScript online submissions for Reverse Integer.
 *
 * Memory Usage: 40.4 MB, less than 19.67% of JavaScript online submissions for Reverse Integer.
 */

const reverse = (x) => {
  if (x > -2147483648 && x < 2147483648) {
    let y =
      x > 0
        ? Number(String(x).split("").reverse().join(""))
        : 0 -
          Number(
            String(0 - x)
              .split("")
              .reverse()
              .join("")
          );
    return y > -2147483648 && y < 2147483648 ? y : 0;
  }
  return 0;
};

1

/*
 * Runtime: 112 ms, faster than 13.44% of JavaScript online submissions for Reverse Integer.
 *
 * Memory Usage: 40.1 MB, less than 19.67% of JavaScript online submissions for Reverse Integer.
 */

const reverse = (x) => {
  const result =
    parseFloat(x.toString().split("").reverse().join("")) * Math.sign(x);

  if (result < Math.pow(-2, 31) || result > Math.pow(2, 31)) return 0;

  return result;
};