From 7e2f5f8fb6bbfdf9289a7b35be2279659e27ef5f Mon Sep 17 00:00:00 2001
From: Rich Harris <richard.a.harris@gmail.com>
Date: Sun, 4 Mar 2018 18:05:33 -0500
Subject: [PATCH] add preloadRoutes function - closes #160

---
 src/runtime/index.ts   | 15 ++++++++++++---
 test/app/app/client.js |  6 ++++--
 test/common/test.js    |  9 ++++++---
 3 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/src/runtime/index.ts b/src/runtime/index.ts
index 43e9ee4..d0fe37d 100644
--- a/src/runtime/index.ts
+++ b/src/runtime/index.ts
@@ -59,9 +59,6 @@ function render(Component: ComponentConstructor, data: any, scroll: ScrollPositi
 			detach(start);
 			detach(end);
 		}
-
-		// preload additional routes
-		routes.reduce((promise: Promise<any>, route) => promise.then(route.load), Promise.resolve());
 	}
 
 	component = new Component({
@@ -268,3 +265,15 @@ export function goto(href: string, opts = { replaceState: false }) {
 		window.location.href = href;
 	}
 }
+
+export function preloadRoutes(pathnames: string[]) {
+	if (!routes) throw new Error(`You must call init() first`);
+
+	return routes
+		.filter(route => {
+			return !pathnames || pathnames.some(pathname => route.pattern.test(pathname));
+		})
+		.reduce((promise: Promise<any>, route) => {
+			return promise.then(route.load);
+		}, Promise.resolve());
+}
\ No newline at end of file
diff --git a/test/app/app/client.js b/test/app/app/client.js
index 7ed4694..d69dd99 100644
--- a/test/app/app/client.js
+++ b/test/app/app/client.js
@@ -1,6 +1,8 @@
-import { init } from '../../../runtime.js';
+import { init, preloadRoutes } from '../../../runtime.js';
 import { routes } from './manifest/client.js';
 
 window.init = () => {
 	return init(document.querySelector('#sapper'), routes);
-};
\ No newline at end of file
+};
+
+window.preloadRoutes = preloadRoutes;
\ No newline at end of file
diff --git a/test/common/test.js b/test/common/test.js
index 9e25b3c..6f47ab4 100644
--- a/test/common/test.js
+++ b/test/common/test.js
@@ -23,6 +23,10 @@ Nightmare.action('init', function(done) {
 	this.evaluate_now(() => window.init(), done);
 });
 
+Nightmare.action('preloadRoutes', function(done) {
+	this.evaluate_now(() => window.preloadRoutes(), done);
+});
+
 function run(env) {
 	describe(`env=${env}`, function () {
 		this.timeout(30000);
@@ -155,7 +159,7 @@ function run(env) {
 			});
 
 			it('navigates to a new page without reloading', () => {
-				return capture(() => nightmare.goto(base).init().wait(400))
+				return capture(() => nightmare.goto(base).init().preloadRoutes())
 					.then(() => {
 						return capture(() => nightmare.click('a[href="/about"]'));
 					})
@@ -189,7 +193,6 @@ function run(env) {
 				return nightmare
 					.goto(`${base}/about`)
 					.init()
-					.wait(200)
 					.then(() => {
 						return capture(() => {
 							return nightmare
@@ -215,7 +218,7 @@ function run(env) {
 			it('reuses prefetch promise', () => {
 				return nightmare
 					.goto(`${base}/blog`)
-					.init().wait(300)
+					.init()
 					.then(() => {
 						return capture(() => {
 							return nightmare