Adds initial pass at preflight.

src/http/any-catchall/_get-preflight.mjs

@@ -0,0 +1,14 @@
+import { join } from 'path'
+import { pathToFileURL } from 'url'
+
+export default async function GetPreflight({ basePath = '' }) {
+  try {
+    const pathToPreflight = pathToFileURL(join(basePath, 'preflight.mjs')).href
+    const { default: preflight } = await import(pathToPreflight)
+    return preflight
+  }
+  catch (error) {
+    return {}
+  }
+}
+

src/http/any-catchall/router.mjs

@@ -10,6 +10,7 @@ import headerTimers from 'header-timers'
 import getModule from './_get-module.mjs'
 import getElements from './_get-elements.mjs'
 import getPageName from './_get-page-name.mjs'
+import getPreflight from './_get-preflight.mjs'
 import isJSON from './_is-json-request.mjs'
 import backfill from './_backfill-params.mjs'
 import render from './_render.mjs'
@@ -26,6 +27,7 @@ export default async function api(options, req) {
   let pagePath = getModule(basePath, 'pages', req.rawPath)
   let apiBaseUsed = basePath
   let pageBaseUsed = basePath
+  let preflight = await getPreflight({ basePath })
 
   if (altPath) {
     let apiPathPart = apiPath && apiPath.replace(path.join(basePath, 'api'), '')
@@ -141,9 +143,7 @@ export default async function api(options, req) {
   let elements = { ...altHeadElements.elements, ...baseHeadElements.elements }
   timers.stop('elements')
 
-  const store = state.json
-    ? state.json
-    : {}
+  const store = Object.assign(preflight(req), state.json ? state.json : {})
 
   function html(str, ...values) {
     const _html = enhance({

test/_get-preflight.mjs

@@ -0,0 +1,19 @@
+import path from 'path'
+import test from 'tape'
+import url from 'url'
+import getPreflight from '../src/http/any-catchall/_get-preflight.mjs'
+const __dirname = path.dirname(url.fileURLToPath(import.meta.url))
+
+test.only('getPreflight', async t => {
+  t.plan(1)
+  const basePath = path.join(__dirname, 'mock-preflight', 'app')
+  const expected = {
+    title: 'About',
+    account: {
+      username: 'Bob Syouruncle',
+      id: '23jk24h24'
+    }
+  }
+  const preflight = await getPreflight({ basePath })
+  t.deepEqual(expected, preflight({ req: { path: '/about' } }), 'Got preflight')
+})

test/mock-preflight/app/preflight.mjs

@@ -0,0 +1,19 @@
+export default function Preflight({ req }) {
+  return {
+    title: getPageTitle(req.path),
+    account: {
+      username: 'Bob Syouruncle',
+      id: '23jk24h24'
+    }
+  }
+}
+
+function getPageTitle(path) {
+  const titleMap = {
+    '/': 'Home',
+    '/about': 'About',
+    '/account': 'My Account'
+  }
+
+  return titleMap[path] || 'My App Name'
+}