Promisify XMLHttpRequest

1 files changed, 33 insertions, 0 deletions

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);
+}