Playwright now offers a UI mode

#​631 — March 24, 2023

Read on the Web

JavaScript Weekly

Speeding Up the JavaScript Ecosystem: npm Scripts — The latest in what has been a fascinating series on finding ‘low hanging fruit’ when it comes to performance in the JavaScript world. The author explains it best himself:

“‘npm scripts’ are executed by JavaScript developers … all the time. Despite their high usage they are not particularly well optimized and add about 400ms of overhead. In this article we were able to bring that down to ~22ms.”
What Marvin does here is a valuable skill for all developers to pick up, and you can enjoy more by going back to the start.

Marvin Hagemeister

Playwright v1.32 – Now with UI Mode — The popular Web testing and automation framework is taking more steps toward ground currently served by tools like Cypress by offering a ‘UI mode’ that lets you explore, run and debug tests in a UI environment, complete with watch mode. ▶️ This video provides a good introduction.


A Grid Component with All the Features & Great Performance — Try our powerful JS data grid component which lets you edit, sort, group and filter datasets with fantastic performance. Includes a TreeGrid, API docs and plenty of demos. Seamless integration with React, Angular & Vue apps.

Bryntum sponsor

Why We Added package.json Support to Deno — Deno shares some provenance with Node.js but till recently it hadn’t focused on supporting Node features like npm modules. But with Node and npm compatibility beginning to improve, the team has faced questions about the runtime’s priorities. Ryan Dahl explains more about their thinking here.

Ryan Dahl

???? In other Deno news, Deno 1.32 has been released with… improved package.json support, and more.

How to Start a React Project in 2023 — There are lots of ways, but this well-regarded author explains the pros and cons of a few approaches, and gives you a few options targeting specific use cases you might have.

Robin Wieruch


GitHub had to update its RSA SSH host key today so you may see security related warnings when pushing and cloning. It’s easy to fix, but check the new fingerprint matches – it’s for your own security.

The New Stack caught up with Svelte’s Rich Harris on SvelteKit and what’s coming for Svelte 4.

The React team shared some cutting edge updates on what they’re working on including React Server Components and an optimizing compiler.

If you were experiencing errors on the official Node site last week, here’s the (detailed) post mortem of why. Config errors and inappropriate caching, mostly.

✨ Did you know there’s a market in fake GitHub stars? Some developers analyzed some repos to learn more about it.

???? Congratulations to Lea Verou on her TC39 appointment. Her efforts to push the Web forward are legendary. Prism is one project you may be aware of.

Make your opinions known on what should be in the next version of Vite.


Docusaurus 2.4
↳ Easy to maintain documentation site generator.

Puppeteer 19.8
↳ Headless Chrome Node.js API.

Neutralinojs 4.11
↳ Lightweight cross-platform desktop app framework.

Qwik 0.23

???? Articles & Tutorials

Buying a Hard-to-Get Bicycle using Playwright — An unusual use case for JavaScript, Playwright, and GitHub Actions, but Maciek managed to buy his bike.

Maciek Palmowski

Snyk Top 10: JavaScript OSS Vulnerabilities — Dive into the most prevalent critical and high open source vulnerabilities found by Snyk scans of JavaScript apps in 2022.

Snyk sponsor

The ‘End’ of Front-End Development? — A recent narrative doing the rounds suggests that large language models like GPT-4 (or even tools like Copilot X) could soon put some developers out of a job — however, Josh is “optimistic about what these AI advancements mean for the future of software development”.

Josh W. Comeau

In related news, Eric Elliott put ChatGPT through its paces to see if it would make for a good JavaScript tutor. It did well — though with mixed results.

Migrating from ts-node to Bun — A look at adopting performance-oriented Bun when you’re used to using TypeScript with Node.js. John runs us through porting a console app from the ts-node approach over to Bun — “a pretty easy process,” he says.

John Reilly

▶  A Pinia Crash Course for BeginnersPinia is a store / state management solution for Vue that does believe in pineapple on pizza.

Alexander Gekov

A Practical Guide to Getting Started with Astro — An extensive walkthrough of Astro that covers all the topics you’ll need to get you started.

Mojtaba Seyedi

???? Test Website Speed Continuously and Rank Higher In Google — You need a fast website to make users happy and meet Google’s Core Web Vitals metrics. Test and optimize with DebugBear.

DebugBear sponsor

Automatic npm Publishing with GitHub Actions and Granular Tokens

Tim Perry

Make Sure You Do This Before Switching to Signals in Angular

Jordan Powell

Six CSS Snippets Every Developer Should Know

Adam Argyle (Google)

???? Code & Tools Easy Webperf Trace Sharing — A quick way to share a performance profile saved from your DevTools, available for up to 90 days with the DevTools perf panel embedded (see example).

paul irish

VueUse: A Collection of Vue Composition Utilities — With over 200 functions targeting both Vue 2 and 3, there’ll be something in this suite of Composition API-based utility functions for you, whether it’s working with state, browser capabilities, animations, Electron, Firebase, and more.

Anthony Fu

Don’t Let Your Issue Tracker Be a Four-Letter Word. Use Shortcut

Shortcut (formerly sponsor

OTPAuth: One Time Password (HOTP/TOTP) Library — When you log in to a site that uses 2FA and you’re asked for some digits from an authentication app, that’s probably a Time-based One-Time Password (or TOTP). This library for Node, Deno, Bun and the browser lets you work with TOTPs and HOTPs from JS.

Héctor Molinero Fernández

Recharts 2.5: Chart Library Built with React and D3 — Easy to deploy with declarative components, native SVG support, and lightweight dependency on D3. Line, bar, scatter, composed, pie, and radar charts are offered. There are lots of examples, complete with code.


DOCX 8.0: Generate Word .docx Files from JavaScript — The code to lay out documents is verbose but there’s a lot of functionality. Here’s a CodePen example and release notesGitHub repo.

Dolan Miu

SvHighlight: Code Syntax Highlighter for Svelte — Powered by Highlight.js, it includes a blurring feature to focus attention on specific areas of code and you an customize it with Tailwind. Try the interactive examples to see the effect.


eslint-formatter-pretty 5.0: Pretty ESLint Formatter — Nicer output than the default. Sort results by severity. Get stylized inline code blocks, and more.

Sindre Sorhus

AWS JWT Verify: Verify JWTs Signed by Amazon Cognito — In both Node.js and the browser.

Amazon Web Services

???? Jobs

Software Engineer (Backend) — Join our “kick ass” team. Our software team operates from 17 countries and we’re always looking for more exceptional engineers.

Sticker Mule

Find JavaScript Jobs with Hired — Hired makes job hunting easy-instead of chasing recruiters, companies approach you with salary details up front. Create a free profile now.


????‍???? Got a job listing to share? Here’s how.

melonJS 15.0
↳ Mature HTML5 game engine.

Marked 4.3
↳ Markdown parser and compiler. (Demo.)

v8go 0.9
↳ Execute JavaScript from Go(lang).

Million 2.1
↳ Fast Virtual DOM to make React faster.

Partytown 0.7.6
↳ Take third-party scripts off the main thread.

???? Bonus Item

Make Bookmarklets — Create and test bookmarklets directly in the browser. Makes an irritating task slightly easier if you need to do it.

Cullan Luther

Flatlogic Admin Templates banner

Maintaining Code Quality with Amazon CodeCatalyst Reports

Amazon CodeCatalyst reports contain details about tests that occur during a workflow run. You can create tests such as unit tests, integration tests, configuration tests, and functional tests. You can use a test report to help troubleshoot a problem during a workflow.


In prior posts in this series, I discussed reading The Unicorn Project, by Gene Kim, and how the main character, Maxine, struggles with a complicated Software Development Lifecycle (SDLC) after joining a new team. One of the challenges she encounters is the difficulties in shipping secure, functioning code without an automated testing mechanism. To quote Gene Kim, “Without automated testing, the more code we write, the more money it takes for us to test.”

Software Developers know that shipping vulnerable or non-functioning code to a production environment is to be avoided at all costs; the monetary impact is high and the toll it takes on team morale can be even greater. During the SDLC, developers need a way to easily identify and troubleshoot errors in their code.

In this post, I will focus on how developers can seamlessly run tests as a part of workflow actions as well as configure unit test and code coverage reports with Amazon CodeCatalyst. I will also outline how developers can access these reports to gain insights into their code quality.


If you would like to follow along with this walkthrough, you will need to:

Have an AWS Builder ID for signing in to CodeCatalyst.
Belong to a CodeCatalyst space and have the Space administrator role assigned to you in that space. For more information, see Creating a space in CodeCatalyst, Managing members of your space, and Space administrator role.
Have an AWS account associated with your space and have the IAM role in that account. For more information about the role and role policy, see Creating a CodeCatalyst service role.


As with the previous posts in the CodeCatalyst series, I am going to use the Modern Three-tier Web Application blueprint. Blueprints provide sample code and CI/CD workflows to help you get started easily across different combinations of programming languages and architectures. To follow along, you can re-use a project you created previously, or you can refer to a previous post that walks through creating a project using the Three-tier blueprint.

Once the project is deployed, CodeCatalyst opens the project overview. This view shows the content of the README file from the project’s source repository, workflow runs, pull requests, etc. The source repository and workflow are created for me by the project blueprint. To view the source code, I select Code → Source Repositories from the left-hand navigation bar. Then, I select the repository name link from the list of source repositories.

Figure 1. List of source repositories including Mythical Mysfits source code.

From here I can view details such as the number of branches, workflows, commits, pull requests and source code of this repo. In this walkthrough, I’m focused on the testing capabilities of CodeCatalyst. The project already includes unit tests that were created by the blueprint so I will start there.

From the Files list, navigate to web → src → components→ __tests__ → TheGrid.spec.js. This file contains the front-end unit tests which simply check if the strings “Good”, “Neutral”, “Evil” and “Lawful”, “Neutral”, “Chaotic” have rendered on the web page. Take a moment to examine the code. I will use these tests throughout the walkthrough.

Figure 2. Unit test for the front-end that test strings have been rendered properly. 

Next, I navigate to the  workflow that executes the unit tests. From the left-hand navigation bar, select CI/CD → Workflows. Then, find ApplicationDeploymentPipeline, expand Recent runs and select  Run-xxxxx . The Visual tab shows a graphical representation of the underlying YAML file that makes up this workflow. It also provides details on what started the workflow run, when it started,  how long it took to complete, the source repository and whether it succeeded.

Figure 3. The Deployment workflow open in the visual designer.

Workflows are comprised of a source and one or more actions. I examined test reports for the back-end in a prior post. Therefore, I will focus on the front-end tests here. Select the build_and_test_frontend action to view logs on what the action ran, its configuration details, and the reports it generated. I’m specifically interested in the Unit Test and Code Coverage reports under the Reports tab:

Figure 4. Reports tab showing line and branch coverage.

Select the report unitTests.xml (you may need to scroll). Here, you can see an overview of this specific report with metrics like pass rate, duration, test suites, and the test cases for those suites:

Figure 5. Detailed report for the front-end tests.

This report has passed all checks.  To make this report more interesting, I’ll intentionally edit the unit test to make it fail. First, navigate back to the source repository and open web → src → components→ __tests__→TheGrid.spec.js. This test case is looking for the string “Good” so change it to say “Best” instead and commit the changes.

Figure 6. Front-End Unit Test Code Change.

This will automatically start a new workflow run. Navigating back to CI/CD →  Workflows, you can see a new workflow run is in progress (takes ~7 minutes to complete).

Once complete, you can see that the build_and_test_frontend action failed. Opening the unitTests.xml report again, you can see that the report status is in a Failed state. Notice that the minimum pass rate for this test is 100%, meaning that if any test case in this unit test ever fails, the build fails completely.

There are ways to configure these minimums which will be explored when looking at Code Coverage reports. To see more details on the error message in this report, select the failed test case.

Figure 7. Failed Test Case Error Message.

As expected, this indicates that the test was looking for the string “Good” but instead, it found the string “Best”. Before continuing, I return to the TheGrid.spec.js file and change the string back to “Good”.

CodeCatalyst also allows me to specify code and branch coverage criteria. Coverage is a metric that can help you understand how much of your source was tested. This ensures source code is properly tested before shipping to a production environment. Coverage is not configured for the front-end, so I will examine the coverage of the back-end.

I select Reports on the left-hand navigation bar, and open the report called backend-coverage.xml. You can see details such as line coverage, number of lines covered, specific files that were scanned, etc.

Figure 8. Code Coverage Report Succeeded.

The Line coverage minimum is set to 70% but the current coverage is 80%, so it succeeds. I want to push the team to continue improving, so I will edit the workflow to raise the minimum threshold to 90%. Navigating back to CI/CD → Workflows → ApplicationDeploymentPipeline, select the Edit button. On the Visual tab, select build_backend. On the Outputs tab, scroll down to Success Criteria and change Line Coverage to 90%.

Figure 9. Configuring Code Coverage Success Criteria.

On the top-right, select Commit. This will push the changes to the repository and start a new workflow run. Once the run has finished, navigate back to the Code Coverage report. This time, you can see it reporting a failure to meet the minimum threshold for Line coverage.

Figure 10. Code Coverage Report Failed.

There are other success criteria options available to experiment with. To learn more about success criteria, see Configuring success criteria for tests.


If you have been following along with this workflow, you should delete the resources you deployed so you do not continue to incur charges. First, delete the two stacks that CDK deployed using the AWS CloudFormation console in the AWS account you associated when you launched the blueprint. These stacks will have names like mysfitsXXXXXWebStack and mysfitsXXXXXAppStack. Second, delete the project from CodeCatalyst by navigating to Project settings and choosing Delete project.


In this post, I demonstrated how Amazon CodeCatalyst can help developers quickly configure test cases, run unit/code coverage tests, and generate reports using CodeCatalyst’s workflow actions. You can use these reports to adhere to your code testing strategy as a software development team. I also outlined how you can use success criteria to influence the outcome of a build in your workflow.  In the next post, I will demonstrate how to configure CodeCatalyst workflows and integrate Software Composition Analysis (SCA) reports. Stay tuned!

About the authors:

Imtranur Rahman

Imtranur Rahman is an experienced Sr. Solutions Architect in WWPS team with 14+ years of experience. Imtranur works with large AWS Global SI partners and helps them build their cloud strategy and broad adoption of Amazon’s cloud computing platform.Imtranur specializes in Containers, Dev/SecOps, GitOps, microservices based applications, hybrid application solutions, application modernization and loves innovating on behalf of his customers. He is highly customer obsessed and takes pride in providing the best solutions through his extensive expertise.

Wasay Mabood

Wasay is a Partner Solutions Architect based out of New York. He works primarily with AWS Partners on migration, training, and compliance efforts but also dabbles in web development. When he’s not working with customers, he enjoys window-shopping, lounging around at home, and experimenting with new ideas.