refactor(joinURL): rewrite with clear syntax and relative ../ support

src/utils.ts

@@ -13,8 +13,6 @@ const PROTOCOL_REGEX = /^[\s\w\0+.-]{2,}:([/\\]{2})?/;
 const PROTOCOL_RELATIVE_REGEX = /^([/\\]\s*){2,}[^/\\]/;
 const PROTOCOL_SCRIPT_RE = /^[\s\0]*(blob|data|javascript|vbscript):$/i;
 const TRAILING_SLASH_RE = /\/$|\/\?|\/#/;
-const JOIN_LEADING_SLASH_RE = /^\.?\//;
-const JOIN_LAST_SEGMENT_RE = /(?:^|\/)[^/]*\/?$/;
 
 /**
  * Check if a path starts with `./` or `../`.
@@ -319,27 +317,51 @@ export function isNonEmptyURL(url: string) {
  *
  * @group utils
  */
-export function joinURL(base: string, ...input: string[]): string {
- let url = base || "";
-
- for (const segment of input.filter((url) => isNonEmptyURL(url))) {
- if (url) {
- const hasAbsoluteBase = url.startsWith("/");
- let _segment = segment;
- _segment = _segment.replace(JOIN_LEADING_SLASH_RE, "");
- while (url.length > 0 && _segment.startsWith("../")) {
- url = url.replace(JOIN_LAST_SEGMENT_RE, "");
- _segment = _segment.slice(3).replace(JOIN_LEADING_SLASH_RE, "");
+export function joinURL(..._input: string[]): string {
+ const input = _input.filter(Boolean);
+
+ const segments: string[] = [];
+
+ let segmentsDepth = 0;
+
+ for (const i of input) {
+ if (!i || i === "/") {
+ continue;
+ }
+ for (const s of i.split("/")) {
+ if (!s || s === ".") {
+ continue;
+ }
+ if (s === "..") {
+ segments.pop();
+ segmentsDepth--;
+ continue;
  }
- url =
- !url && (!hasAbsoluteBase || _segment.startsWith("../"))
- ? _segment
- : withTrailingSlash(url) + _segment;
- } else {
- url = segment;
+ segments.push(s);
+ segmentsDepth++;
  }
  }
 
+ let url = segments.join("/");
+
+ if (segmentsDepth >= 0) {
+ // Preserve leading slash
+ if (input[0]?.startsWith("/") && !url.startsWith("/")) {
+ url = "/" + url;
+ } else if (input[0]?.startsWith("./") && !url.startsWith("./")) {
+ url = "./" + url;
+ }
+ } else {
+ // Add relative prefix
+ url = "../".repeat(-1 * segmentsDepth) + url;
+ }
+
+ // Preserve trailing slash
+ // eslint-disable-next-line unicorn/prefer-at
+ if (input[input.length - 1]?.endsWith("/") && !url.endsWith("/")) {
+ url += "/";
+ }
+
  return url;
 }
 

test/base.test.ts

@@ -4,8 +4,8 @@ import { withBase, withoutBase } from "../src";
 describe("withBase", () => {
  const tests = [
  { base: "/", input: "/", out: "/" },
- { base: "/foo", input: "/", out: "/foo" },
- { base: "/foo/", input: "/", out: "/foo" },
+ { base: "/foo", input: "", out: "/foo" },
+ { base: "/foo/", input: "/", out: "/foo/" },
  { base: "/foo", input: "/bar", out: "/foo/bar" },
  { base: "/base/", input: "/base", out: "/base" },
  { base: "/base", input: "/base/", out: "/base/" },

test/join.test.ts

@@ -5,38 +5,37 @@ describe("joinURL", () => {
  const tests = [
  { input: [], out: "" },
  { input: ["/"], out: "/" },
- // eslint-disable-next-line unicorn/no-null
- { input: [null, "./"], out: "./" },
+ { input: [undefined, "./"], out: "./" },
  { input: ["./", "a"], out: "./a" },
  { input: ["./a", "./b"], out: "./a/b" },
  { input: ["/a"], out: "/a" },
  { input: ["a", "b"], out: "a/b" },
  { input: ["/", "/b"], out: "/b" },
- { input: ["/a", "../b"], out: "/b" },
- { input: ["../a", "../b"], out: "../b" },
- { input: ["../a", "./../b"], out: "../b" },
- { input: ["../a", "./../../b"], out: "b" },
- { input: ["../a", "../../../b"], out: "../b" },
- { input: ["../a", "../../../../b"], out: "../../b" },
- { input: ["../a/", "../b"], out: "../b" },
- { input: ["/a/b/c", "../../d"], out: "/a/d" },
- { input: ["/c", "../../d"], out: "../d" },
- { input: ["/c", ".././../d"], out: "../d" },
  { input: ["a", "b/", "c"], out: "a/b/c" },
  { input: ["a", "b/", "/c"], out: "a/b/c" },
  { input: ["/", "./"], out: "/" },
  { input: ["/", "./foo"], out: "/foo" },
  { input: ["/", "./foo/"], out: "/foo/" },
  { input: ["/", "./foo", "bar"], out: "/foo/bar" },
+
+ // Relative with ../
+ { input: ["/a", "../b"], out: "/b" },
+ { input: ["/a/b/c", "../../d"], out: "/a/d" },
+ { input: ["/a", "../../d"], out: "/d" },
+ { input: ["/a", ".././../d"], out: "/d" },
+ { input: ["/a", "../../../d"], out: "../d" },
+ { input: ["/a/b", "../../../d"], out: "/d" },
+ { input: ["../a", "../b"], out: "b" },
+ { input: ["../a", "./../b"], out: "b" },
+ { input: ["../a", "./../../b"], out: "../b" },
+ { input: ["../a", "../../../b"], out: "../../b" },
+ { input: ["../a", "../../../../b"], out: "../../../b" },
+ { input: ["../a/", "../b"], out: "b" },
  ];
 
  for (const t of tests) {
- test(JSON.stringify(t.input), () => {
- expect(joinURL(...t.input)).toBe(t.out);
+ test(`joinURL(${t.input.map((i) => JSON.stringify(i)).join(", ")}) === ${JSON.stringify(t.out)}`, () => {
+ expect(joinURL(...(t.input as string[]))).toBe(t.out);
  });
  }
-
- test("no arguments", () => {
- expect(joinURL()).toBe("");
- });
 });