Cloudfront Functions — Redirect Rules

function handler(event) {
    var request = event.request;

    if (request.uri !== "/" && (request.uri.endsWith("/") || request.uri.lastIndexOf(".") < request.uri.lastIndexOf("/"))) {
          if (request.uri.endsWith("/")) {
             request.uri = request.uri.concat("index.html");
          } else {
             request.uri = request.uri.concat("/index.html");
          }
     }

    return request
}