Added a polyfill for the URL class on IE

Author: JamesMessinger

package-lock.json

@@ -3,8 +3,12 @@ import { Browsers, BrowsersRecord, Global, Host, OSInfo, OSInfoRecord } from "./
 import { merge, mergeGlobalHost } from "./merge";
 import { toJSON } from "./to-json";
 
-let url = new URL(window.location.href);
-let cwdURL = new URL(".", url);
+// Determine whether this browser supports creating URL objects
+// eslint-disable-next-line @typescript-eslint/brace-style
+const canCreateURL = (() => { try { return Boolean(new URL("http://example.com")); } catch (e) { return false; } })();
+
+const url = createURL(window.location.href);
+const cwdURL = createURL(".", url);
 
 /**
  * Information about the host environment that the code is running in.
@@ -27,6 +31,19 @@ export const host: Host = {
 // Merge the global `host` object (if it exists)
 mergeGlobalHost(host, host.global.host);
 
+/**
+ * Creates a URL object from a URL string
+ */
+function createURL(url: string, base?: URL): URL {
+ if (canCreateURL) {
+ return new URL(url, base);
+ }
+ else {
+ // Poor-man's polyfill for URL on Internet Explorer
+ return { href: base ? base.href : url } as URL;
+ }
+}
+
 /**
  * Returns information about the current Browser host.
  */