Refactor BrowserManager and Converter to load puppeteer-core on demand

Author: yhatt

src/browser/finder.ts

@@ -3,6 +3,8 @@ import { debugBrowserFinder } from '../utils/debug'
 import { isExecutable, normalizeDarwinAppPath } from '../utils/finder'
 import type { Browser } from './browser'
 import { chromeFinder as chrome } from './finders/chrome'
+import { defaultFinders } from './finders/definition'
+import type { FinderName } from './finders/definition'
 import { edgeFinder as edge } from './finders/edge'
 import { firefoxFinder as firefox } from './finders/firefox'
 
@@ -19,19 +21,10 @@ export type BrowserFinder = (
   opts: BrowserFinderOptions
 ) => Promise<BrowserFinderResult>
 
-export type FinderName = keyof typeof availableFindersMap
-
-const availableFindersMap = { chrome, edge, firefox } as const
-
-export const availableFinders = Object.keys(
-  availableFindersMap
-) as readonly FinderName[]
-
-export const defaultFinders = [
-  'chrome',
-  'edge',
-  'firefox',
-] as const satisfies readonly FinderName[]
+const availableFindersMap = { chrome, edge, firefox } as const satisfies Record<
+  FinderName,
+  BrowserFinder
+>
 
 export const findBrowser = async (
   finders: readonly FinderName[] = defaultFinders,

src/browser/finders/definition.ts

@@ -0,0 +1,7 @@
+export const availableFinders = ['chrome', 'edge', 'firefox'] as const
+
+export type FinderName = (typeof availableFinders)[number]
+
+export const defaultFinders = [
+  ...availableFinders,
+] as const satisfies readonly FinderName[]

src/browser/manager.ts

@@ -3,8 +3,10 @@ import { debugBrowser } from '../utils/debug'
 import { createMemoizedPromiseContext } from '../utils/memoized-promise'
 import type { Browser, BrowserProtocol } from './browser'
 import { ChromeCdpBrowser } from './browsers/chrome-cdp'
-import { defaultFinders, findBrowser } from './finder'
-import type { BrowserFinderResult, FinderName } from './finder'
+import { findBrowser } from './finder'
+import type { BrowserFinderResult } from './finder'
+import { defaultFinders } from './finders/definition'
+import type { FinderName } from './finders/definition'
 
 export interface BrowserManagerConfig {
   /** Browser finders */

src/config.ts

@@ -3,8 +3,8 @@ import path from 'node:path'
 import chalk from 'chalk'
 import { cosmiconfig, cosmiconfigSync } from 'cosmiconfig'
 import { osLocale } from 'os-locale'
-import { availableFinders } from './browser/finder'
-import type { FinderName } from './browser/finder'
+import { availableFinders } from './browser/finders/definition'
+import type { FinderName } from './browser/finders/definition'
 import type { BrowserManagerConfig } from './browser/manager'
 import { info, warn, error as cliError } from './cli'
 import { ConvertType, type ConverterOption } from './converter'
@@ -135,7 +135,7 @@ export class MarpCLIConfig {
   browserManagerOption() {
     const finders = (() => {
       const isAvailableFinder = (f: string): f is FinderName =>
-        (availableFinders as string[]).includes(f)
+        availableFinders.includes(f as FinderName)
 
       const browser = this.args.browser ?? this.conf.browser ?? 'auto'
 

src/converter.ts

@@ -62,8 +62,8 @@ export const mimeTypes = {
 export interface ConverterOption {
   allowLocalFiles: boolean
   baseUrl?: string
-  browserManager: BrowserManager
   engine: Engine
+  getBrowserManager: () => BrowserManager | Promise<BrowserManager>
   globalDirectives: { theme?: string } & Partial<TemplateMeta>
   html?: MarpOptions['html']
   imageScale?: number
@@ -130,7 +130,8 @@ export class Converter {
   }
 
   get browser(): Promise<Browser> {
-    return this.options.browserManager.browserForConversion()
+    return (async () =>
+      (await this.options.getBrowserManager()).browserForConversion())()
   }
 
   get template(): Template {

src/marp-cli.ts

@@ -1,6 +1,7 @@
 import chalk from 'chalk'
-import { availableFinders } from './browser/finder'
-import { BrowserManager } from './browser/manager'
+import { availableFinders } from './browser/finders/definition'
+import type { FinderName } from './browser/finders/definition'
+import type { BrowserManager } from './browser/manager'
 import * as cli from './cli'
 import { DEFAULT_PARALLEL, fromArguments } from './config'
 import { Converter, ConvertedCallback, ConvertType } from './converter'
@@ -65,7 +66,7 @@ const coerceBrowser = (browser: string | false) => {
 
   const normalize = (str: string) => str.toLowerCase().trim()
   const isAvailable = (finder: string) =>
-    (availableFinders as string[]).includes(normalize(finder))
+    availableFinders.includes(normalize(finder) as FinderName)
 
   const normalized = normalize(browser)
   if (normalized === '' || normalized === 'auto') return 'auto'
@@ -423,13 +424,20 @@ export const marpCli = async (
     const config = await fromArguments(args)
     if (args.version) return await version(config)
 
-    // Initialize browser manager
-    browserManager = new BrowserManager(config.browserManagerOption())
+    // Initialize browser manager (import is delayed for better performance when not using browser)
+    const browserManagerOption = config.browserManagerOption()
+    const getBrowserManager = async () => {
+      if (!browserManager) {
+        const { BrowserManager } = await import('./browser/manager')
+        browserManager = new BrowserManager(browserManagerOption)
+      }
+      return browserManager
+    }
 
     // Initialize converter
     const converter = new Converter({
       ...(await config.converterOption()),
-      browserManager,
+      getBrowserManager,
     })
     const cvtOpts = converter.options
 
@@ -533,7 +541,9 @@ export const marpCli = async (
           )
 
           // Preview window
-          const preview = new Preview({ browserManager: browserManager! })
+          const preview = new Preview({
+            browserManager: await getBrowserManager(),
+          })
           preview.on('exit', () => res(0))
           preview.on('opening', (location: string) => {
             const loc = location.substring(0, 50)

test/browser/finder.ts

@@ -2,7 +2,8 @@ import path from 'node:path'
 import { ChromeBrowser } from '../../src/browser/browsers/chrome'
 import { ChromeCdpBrowser } from '../../src/browser/browsers/chrome-cdp'
 import { FirefoxBrowser } from '../../src/browser/browsers/firefox'
-import { defaultFinders, findBrowser } from '../../src/browser/finder'
+import { findBrowser } from '../../src/browser/finder'
+import { defaultFinders } from '../../src/browser/finders/definition'
 import { CLIError } from '../../src/error'
 
 afterEach(() => {

test/converter.ts

@@ -65,7 +65,7 @@ describe('Converter', () => {
 
   const instance = (opts: Partial<ConverterOption> = {}) =>
     new Converter({
-      browserManager,
+      getBrowserManager: () => browserManager,
       themeSet,
       allowLocalFiles: false,
       engine: Marp,
@@ -85,7 +85,7 @@ describe('Converter', () => {
       await using browserManager = new BrowserManager({ timeout: 12345 })
 
       const options = {
-        browserManager,
+        getBrowserManager: () => browserManager,
         themeSet,
         allowLocalFiles: true,
         engine: Marp,
@@ -923,7 +923,7 @@ describe('Converter', () => {
 
             await expect(
               pdfInstance({
-                browserManager,
+                getBrowserManager: () => browserManager,
                 output: 'test.pdf',
               }).convertFile(new File(onePath))
             ).rejects.toThrow(TimeoutError)
@@ -944,7 +944,7 @@ describe('Converter', () => {
             })
 
             await pdfInstance({
-              browserManager,
+              getBrowserManager: () => browserManager,
               output: 'test.pdf',
             }).convertFile(new File(onePath))
 
@@ -1229,7 +1229,7 @@ describe('Converter', () => {
               })
 
               await instance({
-                browserManager,
+                getBrowserManager: () => browserManager,
                 output: 'a.png',
                 type: ConvertType.png,
                 imageScale: 0.5,
@@ -1271,7 +1271,7 @@ describe('Converter', () => {
               )
 
               await instance({
-                browserManager,
+                getBrowserManager: () => browserManager,
                 output: 'a.png',
                 type: ConvertType.png,
                 imageScale: 0.5,
@@ -1312,7 +1312,7 @@ describe('Converter', () => {
 
               await expect(
                 instance({
-                  browserManager,
+                  getBrowserManager: () => browserManager,
                   output: 'a.png',
                   type: ConvertType.png,
                   imageScale: 0.5,
@@ -1405,7 +1405,7 @@ describe('Converter', () => {
             })
 
             await instance({
-              browserManager,
+              getBrowserManager: () => browserManager,
               output: 'b.jpg',
               type: ConvertType.jpeg,
               imageScale: 0.25,
@@ -1424,7 +1424,7 @@ describe('Converter', () => {
             writeFileSpy.mockClear()
 
             await instance({
-              browserManager,
+              getBrowserManager: () => browserManager,
               output: 'b.jpg',
               type: ConvertType.jpeg,
               imageScale: 0.25,
@@ -1449,7 +1449,7 @@ describe('Converter', () => {
             })
 
             await instance({
-              browserManager,
+              getBrowserManager: () => browserManager,
               output: 'b.jpg',
               type: ConvertType.jpeg,
               imageScale: 0.25,
@@ -1468,7 +1468,7 @@ describe('Converter', () => {
             writeFileSpy.mockClear()
 
             await instance({
-              browserManager,
+              getBrowserManager: () => browserManager,
               output: 'b.jpg',
               type: ConvertType.jpeg,
               imageScale: 0.25,