Improved file upload

scripts/Utils/fetchWithProgress.ts

@@ -0,0 +1,19 @@
+export function fetchWithProgress(url, opts: RequestInit, onProgress: ((this: XMLHttpRequest, ev: ProgressEvent) => any) | null): Promise<string> {
+	return new Promise((resolve, reject) => {
+		let xhr = new XMLHttpRequest()
+		xhr.open(opts.method || "GET", url)
+
+		for(let k in opts.headers || {}) {
+			xhr.setRequestHeader(k, opts.headers[k])
+		}
+
+		xhr.onload = e => resolve(xhr.responseText)
+		xhr.onerror = reject
+
+		if(xhr.upload && onProgress) {
+			xhr.upload.onprogress = onProgress
+		}
+
+		xhr.send(opts.body)
+	})
+}