Improve href() with a faster trim end splat (#14329)

* Faster trim end splat for href()

* Add changeset

* Remove link to benchmarks

* minor refactors

---------

Co-authored-by: Pedro Cattori <[email protected]>

Author: ngbrown

.changeset/spicy-camels-love.md

@@ -0,0 +1,5 @@
+---
+"react-router": patch
+---
+
+Optimize href() to avoid backtracking regex on splat

packages/react-router/lib/href.ts

@@ -27,13 +27,12 @@ export function href<Path extends keyof Args>(
   ...args: Args[Path]
 ): string {
   let params = args[0];
-  let result = path
-    .replace(/\/*\*?$/, "") // Ignore trailing / and /*, we'll handle it below
+  let result = trimTrailingSplat(path) // Ignore trailing / and /*, we'll handle it below
     .replace(
       /\/:([\w-]+)(\?)?/g, // same regex as in .\router\utils.ts: compilePath().
       (_: string, param: string, questionMark: string | undefined) => {
         const isRequired = questionMark === undefined;
-        const value = params ? params[param] : undefined;
+        const value = params?.[param];
         if (isRequired && value === undefined) {
           throw new Error(
             `Path '${path}' requires param '${param}' but it was not provided`,
@@ -46,11 +45,30 @@ export function href<Path extends keyof Args>(
   if (path.endsWith("*")) {
     // treat trailing splat the same way as compilePath, and force it to be as if it were `/*`.
     // `react-router typegen` will not generate the params for a malformed splat, causing a type error, but we can still do the correct thing here.
-    const value = params ? params["*"] : undefined;
+    const value = params?.["*"];
     if (value !== undefined) {
       result += "/" + value;
     }
   }
 
   return result || "/";
 }
+
+/**
+ * Removes a trailing splat and any number of slashes from the end of the path.
+ *
+ * Benchmarked to be faster than `path.replace(/\/*\*?$/, "")`, which backtracks.
+ */
+function trimTrailingSplat(path: string): string {
+  let i = path.length - 1;
+  let char = path[i];
+  if (char !== "*" && char !== "/") return path;
+
+  // for/break benchmarks faster than do/while
+  i--;
+  for (; i >= 0; i--) {
+    if (path[i] !== "/") break;
+  }
+
+  return path.slice(0, i + 1);
+}