Add solution 593 in Javascript (#133)

Author: ltp88

Diff for: README.md

@@ -499,7 +499,7 @@ _If you like this project, please leave me a star._ ★
 |599|[Minimum Index Sum of Two Lists](https://leetcode.com/problems/minimum-index-sum-of-two-lists/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_599.java) | |Easy | HashMap
 |598|[Range Addition II](https://leetcode.com/problems/range-addition-ii/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_598.java) |  |Easy | 
 |594|[Longest Harmonious Subsequence](https://leetcode.com/problems/longest-harmonious-subsequence/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_594.java) |  |Easy | Array, HashMap
-|593|[Valid Square](https://leetcode.com/problems/valid-square/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_593.java) | |Medium | Math
+|593|[Valid Square](https://leetcode.com/problems/valid-square/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_593.java), [Javascript](./javascript/_593.js) | |Medium | Math
 |592|[Fraction Addition and Subtraction](https://leetcode.com/problems/fraction-addition-and-subtraction/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_592.java) | |Medium | Math
 |591|[Tag Validator](https://leetcode.com/problems/tag-validator/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_591.java) |  |Hard | Stack, String
 |590|[N-ary Tree Postorder Traversal](https://leetcode.com/problems/n-ary-tree-postorder-traversal/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_590.java) | |Easy| DFS, recursion

Diff for: javascript/_593.js

@@ -0,0 +1,42 @@
+/**
+ * @param {number[]} p1
+ * @param {number[]} p2
+ * @param {number[]} p3
+ * @param {number[]} p4
+ * @return {boolean}
+ */
+
+//     const d12 = distanceSquare(p1, p2)
+//     const d13 = distanceSquare(p1, p3)
+//     const d14 = distanceSquare(p1, p4)
+//     const d23 = distanceSquare(p2, p3)
+//     const d24 = distanceSquare(p2, p4)
+//     const d34 = distanceSquare(p3, p4)
+
+//     if (d12 === 0 || d13 === 0 || d14 === 0) return false
+
+//     // 1  2
+//     // 3  4
+//     if (d12 === d13 && d12 + d13 === d14 && d23 === d24 + d34) return true
+
+//     // 1  2
+//     // 4  3
+//     if (d12 === d14 && d12 + d14 === d13 && d24 === d34 + d23) return true
+
+//     // 1  3
+//     // 4  2
+//     if (d13 === d14 && d13 + d14 === d12 && d34 === d23 + d24) return true
+
+var validSquare = function (p1, p2, p3, p4) {
+  function distanceSquare(a, b) {
+    return (a[0] - b[0]) * (a[0] - b[0]) + (a[1] - b[1]) * (a[1] - b[1])
+  }
+
+  const ds = [distanceSquare(p1, p2), distanceSquare(p1, p3), distanceSquare(p1, p4), distanceSquare(p2, p3), distanceSquare(p2, p4), distanceSquare(p3, p4)].sort((a, b) => a - b)
+
+  for (var i = 0; i < 3; i++) if (ds[i] !== ds[i + 1] || ds[i] === 0) return false
+
+  if (ds[4] === ds[5] && ds[4] === ds[0] * 2) return true
+
+  return false
+}