Autoopen login modal when it contains modal=login query string (#1604)

frontend/src/components/Navbar/Navbar.jsx

@@ -3,6 +3,7 @@ import { connect } from "react-redux"
 import * as overlay from "../../reducers/overlay"
 import RegisterButton from "../RegisterButton"
 import SignInButton from "../SignInButton"
+import SignInModalAutoOpen from "../SignInModalAutoOpen"
 import NavbarBranding from "./NavbarBranding"
 import NavbarExtraMenu from "./NavbarExtraMenu"
 import NavbarNotificationsDropdown from "./NavbarNotificationsDropdown"
@@ -96,6 +97,7 @@ export function Navbar({
         {!user && !authDelegated && (
           <RegisterButton className="btn-navbar-register" />
         )}
+        {!user && !authDelegated && <SignInModalAutoOpen />}
       </div>
     </div>
   )

frontend/src/components/SignInModalAutoOpen.js

@@ -0,0 +1,18 @@
+import React from "react"
+import modal from "../services/modal"
+import SignInModal from "./sign-in"
+
+class SignInModalAutoOpen extends React.Component {
+  componentDidMount() {
+    const query = window.document.location.search
+    if (query === "?modal=login") {
+      window.setTimeout(() => modal.show(<SignInModal />), 300)
+    }
+  }
+
+  render() {
+    return null
+  }
+}
+
+export default SignInModalAutoOpen