add es6 code for breadth-first-search

06_breadth-first_search/es6/01_breadth-first_search.js

@@ -0,0 +1,32 @@
+const graph = {};
+graph.you = ['alice', 'bob', 'claire'];
+graph.bob = ['anuj', 'peggy'];
+graph.alice = ['peggy'];
+graph.claire = ['thom', 'jonny'];
+graph.anuj = [];
+graph.peggy = [];
+graph.thom = [];
+
+const isSeller = name => name[name.length - 1] === 'm';
+
+const search = (name, graph) => {
+  const iter = (waited, visited) => {
+    if (waited.length === 0) {
+      return false;
+    }
+    const [current, ...rest] = waited;
+    if (visited.has(current)) {
+      return iter(rest, visited);
+    }
+    if (isSeller(current)) {
+      console.log(`${current} is a mango seller!`);
+      return true;
+    }
+    visited.add(current);
+    const personFriends = graph[current];
+    return iter([...rest, ...personFriends], visited);
+  };
+  return iter(graph[name], new Set());
+};
+
+search('you');