Backport changes from Cloudproxy (#11)

src/utils.ts

@@ -0,0 +1,31 @@
+import * as fs from 'fs'
+import * as Path from 'path'
+import { promisify } from 'util'
+
+export const sleep = promisify(setTimeout)
+
+// recursive fs.rmdir needs node version 12:
+// https://github.com/ngosang/FlareSolverr/issues/5#issuecomment-655572712
+export function deleteFolderRecursive(path: string) {
+  if (fs.existsSync(path)) {
+    fs.readdirSync(path).forEach((file) => {
+      const curPath = Path.join(path, file)
+      if (fs.lstatSync(curPath).isDirectory()) { // recurse
+        deleteFolderRecursive(curPath)
+      } else { // delete file
+        fs.unlinkSync(curPath)
+      }
+    })
+    fs.rmdirSync(path)
+  }
+}
+
+export const removeEmptyFields = (o: Record<string, any>): typeof o => {
+  const r: typeof o = {}
+  for (const k in o) {
+    if (o[k] !== undefined) {
+      r[k] = o[k]
+    }
+  }
+  return r
+}