4kyu(js): add „Sort binary tree by levels“

Signed-off-by: Matej Focko <mfocko@redhat.com>

4kyu/sort_binary_tree_by_levels/solution.js

@@ -0,0 +1,18 @@
+function treeByLevels (rootNode) {
+	let queue = [rootNode];
+  let values = [];
+
+  while (queue.length > 0) {
+    let node = queue.shift();
+    if (node === null) {
+      continue;
+    }
+
+    values.push(node.value);
+
+    queue.push(node.left);
+    queue.push(node.right);
+  }
+
+  return values;
+}

README.md

@@ -49,6 +49,7 @@
 - [Priori Incantatem](https://www.codewars.com/kata/574d0b01b4b769b207000ca3) - [solution](4kyu/priori_incantatem)
 - [ES5 Generators(i)](https://www.codewars.com/kata/53c29a6abb5187180d000b65) - [solution](4kyu/es5_generators_i)
 - [Remove Zeros](https://www.codewars.com/kata/52aae14aa7fd03d57400058f) - [solution](4kyu/remove_zeros)
+- [Sort binary tree by levels](https://www.codewars.com/kata/52bef5e3588c56132c0003bc) - [solution](4kyu/sort_binary_tree_by_levels)
 
 ### TS