Add JavaScript and TypeScript code of preorder traversal (Chapter of Backtracking) (#490)

* Add JavaScript and TypeScript code of preorder traversal (Chapter of Backtracking)

* Update preorder_traversal_iii_compact.ts

codes/javascript/chapter_backtracking/preorder_traversal_i_compact.js

@@ -0,0 +1,33 @@
+/**
+ * File: preorder_traversal_i_compact.js
+ * Created Time: 2023-05-09
+ * Author: Justin (xiefahit@gmail.com)
+ */
+
+const { arrToTree } = require('../modules/TreeNode');
+const { printTree } = require('../modules/PrintUtil');
+
+/* 前序遍历：例题一 */
+function preOrder(root, res) {
+  if (root === null) {
+    return;
+  }
+  if (root.val === 7) {
+    // 记录解
+    res.push(root);
+  }
+  preOrder(root.left, res);
+  preOrder(root.right, res);
+}
+
+// Driver Code
+const root = arrToTree([1, 7, 3, 4, 5, 6, 7]);
+console.log("\n初始化二叉树");
+printTree(root);
+
+// 前序遍历
+const res = [];
+preOrder(root, res);
+
+console.log("\n输出所有值为 7 的节点");
+console.log(res.map(node => node.val));