solutions/0028-implement-strstr.js

/**
 * 28. Implement strStr()
 * https://leetcode.com/problems/implement-strstr/
 * Difficulty: Easy
 *
 * Return the index of the first occurrence of needle in haystack, or -1 if needle
 * is not part of haystack.
 *
 * Clarification:
 * - What should we return when needle is an empty string? This is a great question
 *   to ask during an interview.
 *
 * - For the purpose of this problem, we will return 0 when needle is an empty string.
 *   This is consistent to C's strstr() and Java's indexOf().
 */

/**
 * @param {string} haystack
 * @param {string} needle
 * @return {number}
 */
var strStr = function(haystack, needle) {
  if (!needle) return 0;
  const split = haystack.split(needle);
  return split.length > 1 ? split[0].length : -1;
};