From 84762894c86a825d9948556ce462f3930cac1775 Mon Sep 17 00:00:00 2001
From: Matthias Schiffer <mschiffer@universe-factory.net>
Date: Wed, 31 Oct 2018 15:33:52 +0100
Subject: Promisify XMLHttpRequest

---
 src/index.ts | 16 +++++-----------
 src/util.ts  | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+), 11 deletions(-)

(limited to 'src')

diff --git a/src/index.ts b/src/index.ts
index 3e7f33d..b4109e6 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,23 +1,17 @@
 import MapData from './model/data/MapData';
 
+import { getJSON } from './util';
 import { loadMap } from './view/map';
 import Renderer from './view/renderer/Renderer';
 
-window.onload = () => {
+window.onload = async () => {
 	const canvas = document.getElementById('rpgedit') as HTMLCanvasElement;
 	if (!canvas)
 		return;
 
 	const renderer = new Renderer(canvas);
 
-	const xhr = new XMLHttpRequest();
-
-	xhr.addEventListener('load', async function() {
-		const map = new MapData(JSON.parse(this.responseText));
-		const mapView = await loadMap(renderer, map);
-		mapView.render();
-	});
-
-	xhr.open('GET', 'resources/map/test.json', true);
-	xhr.send();
+	const map = new MapData(await getJSON('resources/map/test.json'));
+	const mapView = await loadMap(renderer, map);
+	mapView.render();
 };
diff --git a/src/util.ts b/src/util.ts
index 7129b2b..29c707e 100644
--- a/src/util.ts
+++ b/src/util.ts
@@ -45,3 +45,36 @@ export class Listenable<T extends any[]> {
 		this.listeners.forEach((l) => l(...args));
 	}
 }
+
+export function get(url: string): Promise<XMLHttpRequest> {
+	return new Promise((resolve, reject) => {
+		const xhr = new XMLHttpRequest();
+
+		const handleError = () => {
+			if (xhr.readyState !== xhr.DONE) {
+				reject(new Error('HTTP request ended in state ' + xhr.readyState));
+				return;
+			}
+
+			reject(new Error('HTTP request returned status ' + xhr.status));
+		};
+
+		xhr.addEventListener('error', handleError);
+
+		xhr.addEventListener('load', () => {
+			if (xhr.readyState !== xhr.DONE || xhr.status !== 200) {
+				handleError();
+				return;
+			}
+
+			resolve(xhr);
+		});
+
+		xhr.open('GET', url, true);
+		xhr.send();
+	});
+}
+
+export async function getJSON(url: string): Promise<any> {
+	return JSON.parse((await get(url)).responseText);
+}
-- 
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