solutions/0065-valid-number.js

/**
 * 65. Valid Number
 * https://leetcode.com/problems/valid-number/
 * Difficulty: Hard
 *
 * Given a string s, return whether s is a valid number.
 *
 * For example, all the following are valid numbers: "2", "0089", "-0.1", "+3.14", "4.", "-.9",
 * "2e10", "-90E3", "3e+7", "+6e-1", "53.5e93", "-123.456e789", while the following are not
 * valid numbers: "abc", "1a", "1e", "e3", "99e2.5", "--6", "-+3", "95a54e53".
 *
 * Formally, a valid number is defined using one of the following definitions:
 * - An integer number followed by an optional exponent.
 * - A decimal number followed by an optional exponent.
 *
 * An integer number is defined with an optional sign '-' or '+' followed by digits.
 * A decimal number is defined with an optional sign '-' or '+' followed by one of the
 * following definitions:
 * - Digits followed by a dot '.'.
 * - Digits followed by a dot '.' followed by digits.
 * - A dot '.' followed by digits.
 * - An exponent is defined with an exponent notation 'e' or 'E' followed by an integer number.
 *
 * The digits are defined as one or more digits.
 */

/**
 * @param {string} s
 * @return {boolean}
 */
var isNumber = function(s) {
  return s.trim().length && !isNaN(s.trim()) && !s.includes('Infinity');
};