Node script to open a URL in an existing tab in a Chromium browser, similar to create-react-app's dev server.

openBrowser.ts

// Reference: https://github.com/facebook/create-react-app/blob/main/packages/react-dev-utils/openBrowser.js
import { execSync } from "child_process";
import open from "open";
import defaultBrowserId from "default-browser-id";
import path from "path";

async function startBrowserProcess(url: string) {
  const shouldTryOpenChromiumWithAppleScript = process.platform === "darwin";

  if (shouldTryOpenChromiumWithAppleScript) {
    const supportedChromiumBrowsers: Record<string, string> = {
      "com.google.chrome": "Google Chrome",
      "com.google.chrome.beta": "Google Chrome Beta",
      "com.google.chrome.canary": "Google Chrome Canary",
      "com.microsoft.edgemac": "Microsoft Edge",
      "com.brave.browser": "Brave Browser",
      "org.chromium.chromium": "Chromium",
    };

    const defaultBrowserBundleId = (await defaultBrowserId()) as string;

    const chromiumBrowser =
      supportedChromiumBrowsers[defaultBrowserBundleId.toLowerCase()];

    const baseUrl = new URL(url).origin;

    if (typeof chromiumBrowser === "string") {
      try {
        // Try our best to reuse existing tab
        // on OSX Chromium-based browser with AppleScript
        execSync('ps cax | grep "' + chromiumBrowser + '"');

        const appleScriptPath = path.join(
          __dirname,
          "openChrome.applescript"
        );
        execSync(
          `osascript ${appleScriptPath} "${baseUrl}" "${encodeURI(
            url
          )}" "${chromiumBrowser}"`,
          {
            cwd: __dirname,
            stdio: "ignore",
          }
        );
        return true;
      } catch (err) {
        // Ignore errors.
      }
    }
  }

  // Fallback to open
  // (It will always open new tab)
  try {
    open(url).catch(() => {}); // Prevent `unhandledRejection` error.
    return true;
  } catch (err) {
    return false;
  }
}

export function openBrowser(url: string) {
  return startBrowserProcess(url);
}

openChrome.applescript

(*
Reference: https://github.com/facebook/create-react-app/blob/main/packages/react-dev-utils/openChrome.applescript
*)
property targetTab : null
property targetTabIndex : -1
property targetWindow : null
property theProgram : "Google Chrome"

on run argv
	set baseURL to item 1 of argv
	set fullURL to item 2 of argv
	
	-- Allow requested program to be optional,
	-- default to Google Chrome
	if (count of argv) > 2 then
		set theProgram to item 3 of argv
	end if
	
	using terms from application "Google Chrome"
		tell application theProgram
			
			if (count every window) = 0 then
				make new window
			end if
			
			-- 1: Looking for tab running current baseURL
			-- then, set tab URL to fullURL
			-- then return
			set found to my lookupTabWithUrl(baseURL)
			log (found)
			if found then
				set targetWindow's active tab index to targetTabIndex
				set URL of targetTab to fullURL
				tell targetWindow to activate
				set index of targetWindow to 1
				return
			end if
			
			-- 2: Looking for Empty tab
			-- In case baseURL tab was not found
			-- We try to find an empty tab instead
			set found to my lookupTabWithUrl("chrome://newtab/")
			if found then
				set targetWindow's active tab index to targetTabIndex
				set URL of targetTab to fullURL
				tell targetWindow to activate
				return
			end if
			
			-- 3: Create new tab
			-- both baseURL and empty tab were not found
			-- make a new tab with url
			tell window 1
				activate
				make new tab with properties {URL:fullURL}
			end tell
		end tell
	end using terms from
end run

-- Function:
-- Lookup tab with given url
-- if found, store tab, index, and window in properties
-- (properties were declared on top of file)
on lookupTabWithUrl(lookupUrl)
	using terms from application "Google Chrome"
		tell application theProgram
			-- Find a tab with the given url
			set found to false
			set theTabIndex to -1
			repeat with theWindow in every window
				set theTabIndex to 0
				repeat with theTab in every tab of theWindow
					set theTabIndex to theTabIndex + 1
					if (theTab's URL as string) contains lookupUrl then
						-- assign tab, tab index, and window to properties
						set targetTab to theTab
						set targetTabIndex to theTabIndex
						set targetWindow to theWindow
						set found to true
						exit repeat
					end if
				end repeat
				
				if found then
					exit repeat
				end if
			end repeat
		end tell
	end using terms from
	return found
end lookupTabWithUrl