feat(prerender): Adding the prerender-external cli flag

* feat(prerender): Adding the prerender-external option to use the VNODES with external prerenderer

* feat(prerender): Adding the prerender-external option tests

* feat(prerender): Adding the prerender-external option - removed index html check and added documentation

Author: DominicBoettger

src/cli/parse-flags.ts

@@ -170,6 +170,7 @@ const ARG_OPTS = {
     'log',
     'open',
     'prerender',
+    'prerender-external',
     'prod',
     'profile',
     'service-worker',

src/cli/test/parse-flags.spec.ts

@@ -360,6 +360,12 @@ describe('parseFlags', () => {
     expect(flags.prerender).toBe(true);
   });
 
+  it('should parse --prerender-external', () => {
+    process.argv[2] = '--prerender-external';
+    const flags = parseFlags(process);
+    expect(flags.prerenderExternal).toBe(true);
+  });
+
   it('should parse --root', () => {
     process.argv[2] = '--root';
     process.argv[3] = 'custom-www';

src/client/platform-main-legacy.ts

@@ -123,7 +123,7 @@ export function createPlatformMainLegacy(namespace: string, Context: d.CoreConte
     }
   };
 
-  if (_BUILD_.prerenderClientSide) {
+  if (_BUILD_.prerenderClientSide || _BUILD_.prerenderExternal) {
     // if the HTML was generated from prerendering
     // then let's walk the tree and generate vnodes out of the data
     createVNodesFromSsr(plt, domApi, rootElm);

src/client/platform-main.ts

@@ -270,7 +270,7 @@ export const createPlatformMain = (namespace: string, Context: d.CoreContext, wi
     }
   };
 
-  if (_BUILD_.prerenderClientSide) {
+  if (_BUILD_.prerenderClientSide || _BUILD_.prerenderExternal) {
     // if the HTML was generated from prerendering
     // then let's walk the tree and generate vnodes out of the data
     createVNodesFromSsr(plt, domApi, rootElm);

src/compiler/prerender/prerender-app.ts

@@ -39,6 +39,14 @@ export function shouldPrerender(config: d.Config) {
   return (outputTargets.length > 0);
 }
 
+/**
+ * shouldPrerenderExternal
+ * @description Checks if the cli flag has been set that a external prerenderer will be used
+ * @param config build config
+ */
+export function shouldPrerenderExternal(config: d.Config) {
+  return config.flags && config.flags.prerenderExternal;
+}
 
 async function prerenderOutputTarget(config: d.Config, compilerCtx: d.CompilerCtx, buildCtx: d.BuildCtx, outputTarget: d.OutputTargetWww, entryModules: d.EntryModule[]) {
   // if there was src index.html file, then the process before this one

src/declarations/build-conditionals.ts

@@ -23,6 +23,7 @@ export interface BuildConditionals {
   // ssr
   ssrServerSide: boolean;
   prerenderClientSide: boolean;
+  prerenderExternal: boolean;
 
   // encapsulation
   styles: boolean;

src/declarations/config.ts

@@ -221,6 +221,7 @@ export interface ConfigFlags {
   open?: boolean;
   port?: number;
   prerender?: boolean;
+  prerenderExternal?: boolean;
   prod?: boolean;
   profile?: boolean;
   root?: string;

src/util/build-conditionals.ts

@@ -1,7 +1,7 @@
 import * as d from '../declarations';
 import { DEFAULT_STYLE_MODE, ENCAPSULATION, MEMBER_TYPE, PROP_TYPE } from './constants';
 import { isTsFile } from '../compiler/util';
-import { shouldPrerender } from '../compiler/prerender/prerender-app';
+import { shouldPrerender, shouldPrerenderExternal } from '../compiler/prerender/prerender-app';
 
 
 export function getDefaultBuildConditionals(): d.BuildConditionals {
@@ -14,6 +14,7 @@ export function getDefaultBuildConditionals(): d.BuildConditionals {
     slotPolyfill: true,
     ssrServerSide: true,
     prerenderClientSide: true,
+    prerenderExternal: false,
     devInspector: true,
     hotModuleReplacement: true,
     verboseError: true,
@@ -89,6 +90,7 @@ export async function setBuildConditionals(
     cssVarShim: false,
     ssrServerSide: false,
     prerenderClientSide: false,
+    prerenderExternal: false,
     shadowDom: false,
     scoped: false,
     slotPolyfill: false,
@@ -133,6 +135,7 @@ export async function setBuildConditionals(
     // modern build
     coreBuild.browserModuleLoader = true;
     coreBuild.prerenderClientSide = shouldPrerender(config);
+    coreBuild.prerenderExternal = shouldPrerenderExternal(config);
     compilerCtx.lastBuildConditionalsBrowserEsm = coreBuild;
 
   } else if (coreId === 'core.pf') {
@@ -142,6 +145,7 @@ export async function setBuildConditionals(
     coreBuild.polyfills = true;
     coreBuild.cssVarShim = true;
     coreBuild.prerenderClientSide = shouldPrerender(config);
+    coreBuild.prerenderExternal = shouldPrerenderExternal(config);
     compilerCtx.lastBuildConditionalsBrowserEs5 = coreBuild;
 
   } else if (coreId === 'esm.es5') {