refactor promise, geneerators, global object

1-js/09-async/04-promise-error-handling/head.html

@@ -0,0 +1,41 @@
+<script>
+function loadScript(src) {
+  return new Promise(function(resolve, reject) {
+    let script = document.createElement('script');
+    script.src = src;
+
+    script.onload = () => resolve(script);
+    script.onerror = () => reject(new Error("Script load error: " + src));
+
+    document.head.append(script);
+  });
+}
+
+class HttpError extends Error {
+  constructor(response) {
+    super(`${response.status} for ${response.url}`);
+    this.name = 'HttpError';
+    this.response = response;
+  }
+}
+
+function loadJson(url) {
+  return fetch(url)
+    .then(response => {
+      if (response.status == 200) {
+        return response.json();
+      } else {
+        throw new HttpError(response);
+      }
+    })
+}
+</script>
+
+<style>
+.promise-avatar-example {
+  border-radius: 50%;
+  position: fixed;
+  left: 10px;
+  top: 10px;
+}
+</style>