Add Backend call from frontend

frontend/src/App.tsx

@@ -2,14 +2,34 @@ import React, { useState, useEffect } from "react";
 import axios from "axios";
 
 export default function App() {
+  let [blocks, setBlocks] = useState([]);
+
+  let backendUrl: string = process.env.BACKEND_ADDRESS!;
+
+  if (backendUrl === undefined) {
+    throw Error("backend address not specified in ENV variable");
+  }
+
+  console.log(backendUrl);
+
+  async function fetchBlocks() {
+    let result = await axios(backendUrl);
+    return result.data.Blocks;
+  }
+
   useEffect(() => {
-    axios.get("https://baconipsum.com/api/?type=meat-and-filler").then(res => {
+    fetchBlocks().then(blocks => {
-      console.log(res.data);
+      setBlocks(blocks);
     });
+  }, []);
+
+  let blocksComponent = blocks.map(block => {
+    return <li key={block.hash}>{block.hash}</li>;
   });
+
   return (
     <div>
-      <h1>Hello from App!</h1>
+      <h1>{blocksComponent}</h1>
     </div>
   );
 }