astro/dist/core/routing/trailing-slash-handler.js

Astro is a modern site builder with web best practices, performance, and DX front-of-mind.

import { appendForwardSlash, collapseDuplicateTrailingSlashes, hasFileExtension, isInternalPath, removeTrailingForwardSlash } from "@astrojs/internal-helpers/path";
import { prepareResponse } from "../app/prepare-response.js";
import { redirectTemplate } from "./3xx.js";
import { rejectInvalidEncoding } from "./invalid-encoding.js";
/**
* Handles trailing-slash normalization for incoming requests. If the
* request's pathname does not match the manifest's configured
* `trailingSlash` policy, a redirect `Response` is returned. Otherwise,
* returns `undefined` so the caller can continue processing the request.
* Paths encoded too many times to decode get a 400 instead of a redirect.
*/
export function handleTrailingSlash(state) {
	const invalidEncodingResponse = rejectInvalidEncoding(state);
	if (invalidEncodingResponse) {
		return invalidEncodingResponse;
	}
	// Use a fresh URL parse from the raw request so we see the
	// un-normalized pathname (e.g. duplicate slashes like `///`).
	// state.url has already been normalized by the FetchState
	// constructor, which would hide the redirect targets.
	const url = new URL(state.request.url);
	const redirect = redirectTrailingSlash(state.manifest.trailingSlash, url.pathname);
	// Not a redirect.
	if (redirect === url.pathname) {
		return undefined;
	}
	const addCookieHeader = state.renderOptions.addCookieHeader;
	const status = state.request.method === "GET" ? 301 : 308;
	const location = redirect + url.search;
	const response = new Response(redirectTemplate({
		status,
		relativeLocation: location,
		absoluteLocation: location,
		from: state.request.url
	}), {
		status,
		headers: { location }
	});
	prepareResponse(response, { addCookieHeader });
	return response;
}
function redirectTrailingSlash(trailingSlash, pathname) {
	// Ignore root and internal paths
	if (pathname === "/" || isInternalPath(pathname)) {
		return pathname;
	}
	// Redirect multiple trailing slashes to collapsed path
	const path = collapseDuplicateTrailingSlashes(pathname, trailingSlash !== "never");
	if (path !== pathname) {
		return path;
	}
	if (trailingSlash === "ignore") {
		return pathname;
	}
	if (trailingSlash === "always" && !hasFileExtension(pathname)) {
		return appendForwardSlash(pathname);
	}
	if (trailingSlash === "never") {
		return removeTrailingForwardSlash(pathname);
	}
	return pathname;
}