Download most recent Chrome build

download-chrome.ts

import { createWriteStream, ensureDir } from "fs-extra"
import got from "got"
import { Stream } from "stream"

export type Platform =
  | "Win_x64"
  | "Win"
  | "Mac"
  | "Mac_Arm"
  | "Linux_x64"
  | "Android" // etc

export interface BuildParams {
  platform: Platform
}

export interface SnapshotParams {
  platform: Platform
  build: string | number
  filename: string
}

export interface DownloadParams {
  dest: string
  platform: Platform
  build?: string | number
}

/**
 * Define the base Google storage url.
 * @type {string}
 */
const BASE_URL: string = `https://www.googleapis.com/download/storage/v1/b/chromium-browser-snapshots/o`

/**
 * Prepares a valid snapshot filename from platform.
 *
 * @param {Platform} platform
 * @return {string}
 */
const getSnapshotFilename = (platform: Platform): string =>
  `chrome-${platform.split(`_`)[0].toLowerCase()}.zip`

/**
 * Returns the most current build version for a specific platform.
 *
 * @param {"Win_x64" | "Win" | "Mac" | "Mac_Arm" | "Linux_x64" | "Android"} platform
 * @return {Promise<string>}
 */
export const fetchBuild = async ({ platform }: BuildParams): Promise<string> =>
  got(`${BASE_URL}/${platform}%2FLAST_CHANGE?generation=0&alt=media`).text()

/**
 * Begins streaming the snapshot archive file.
 *
 * @param {"Win_x64" | "Win" | "Mac" | "Mac_Arm" | "Linux_x64" | "Android"} platform
 * @param {string | number} build
 * @param {string} filename
 * @return {Stream}
 */
export const fetchSnapshot = ({
  platform,
  build,
  filename
}: SnapshotParams): Stream =>
  got.stream(
    `${BASE_URL}/${platform}%2F${build}%2F${filename}?generation=0&alt=media`
  )

/**
 * Primary entrypoint to begin a browser download.
 * Must define a target destination and platform.
 * Browser build version can optionally be provided, or falls back to most current.
 * Returns the path to the downloaded file, or rejects with an error.
 *
 * @param {string} dest
 * @param {"Win_x64" | "Win" | "Mac" | "Mac_Arm" | "Linux_x64" | "Android"} platform
 * @param {string | number | undefined} build
 * @return {Promise<string>}
 */
export const downloadBrowser = async ({
  dest,
  platform,
  build
}: DownloadParams): Promise<string> => {
  const params: SnapshotParams = {
    platform,
    build: build ?? (await fetchBuild({ platform })),
    filename: getSnapshotFilename(platform)
  }
  const pathToSnapshot: string = `${dest}/${params.filename}`
  await ensureDir(dest)
  await new Promise((resolve, reject) => {
    fetchSnapshot(params)
      .on("error", reject)
      .pipe(
        createWriteStream(pathToSnapshot)
          .on("error", reject)
          .on("finish", resolve)
      )
  })
  return pathToSnapshot
}

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