22w2: add 28 js solution

Author: swiftwind0405

README.md

@@ -414,7 +414,7 @@
 |31|[Next Permutation](https://leetcode.com/problems/next-permutation/)| |Medium|
 |30|[Substring with Concatenation of All Words](https://leetcode.com/problems/substring-with-concatenation-of-all-words/)| |Hard|
 |29|[Divide Two Integers](https://leetcode.com/problems/divide-two-integers/)| |Medium|
-|28|[Implement strStr()](https://leetcode.com/problems/implement-strstr/)| |Easy|
+|28|[Implement strStr()](https://leetcode.com/problems/implement-strstr/)| [js](./algorithms/implementStrstr/solution.js) |Easy|
 |27|[Remove Element](https://leetcode.com/problems/remove-element/)| [js](./algorithms/removeElement/removeElement.js) [python](./algorithms/removeElement/removeElement.python) |Easy|
 |26|[Remove Duplicates from Sorted Array](https://leetcode.com/problems/remove-duplicates-from-sorted-array/)| [java](./algorithms/removeDuplicatesFromSortedArray/Solution.java), [js](./algorithms/removeDuplicatesFromSortedArray/Solution.js)  |Easy|
 |25|[Reverse Nodes in k-Group](https://leetcode.com/problems/reverse-nodes-in-k-group/)| |Hard|

algorithms/implementStrstr/solution.js

@@ -0,0 +1,28 @@
+// 解法一：用 js 现成的 indexOf api
+var strStr = function(haystack, needle) {
+    if(!needle) return 0;
+    return haystack.indexOf(needle)
+};
+
+
+// TODO: 解法二：自己实现
+// var strStr = function(haystack, needle) {
+//     // 不存在或者相等时，返回0
+//     if (!needle || needle === haystack) return 0;
+//     let h = 0, n = 0, index = 0;
+//     while (h < haystack.length && haystack.length < needle.length) {
+//         while (haystack[h] === needle[n] && n < needle.length) {
+//             if (index === 0) {
+//                 index = h
+//             }
+//             n = n + 1;
+//         }
+//         if (n === needle.length) {
+//             return index;
+//         } else {
+//             h = h + 1;
+//         }
+//     }
+//     // 找不到或者要查找的字符串大于自己的时候，返回-1
+//     return -1;
+// };