-
SurveyJS
Open-Source JSON Form Builder to Create Dynamic Forms Right in Your App. With SurveyJS form UI libraries, you can build and style forms in a fully-integrated drag & drop form builder, render them in your JS app, and store form submission data in any backend, inc. PHP, ASP.NET Core, and Node.js.
-
-
There are a wide variety of libraries you can use to test your code. You'll need a test runner and, usually, a testing utility. For low-level or small projects, I recommend uvu as a test runner and uvu/assert as a testing utility, both of which work in either Node.js or the browser.
For low-level code (i.e. anything involving bit twiddling, binary encoding, etc.), you'll want to use the profiler in Node.js (your code editor may have support) or Chrome (see this article). This guide to performance in the V8 engine may help.
Beyond testing your code, it's an excellent idea to write your library in TypeScript. Type errors are among the most common type of mistake in JavaScript, so using TypeScript will almost always reduce development time and may occasionally prevent you from publishing broken code if you forget to add a test. Moreover, the excellent TypeScript compiler will allow you to avoid using a bundler when publishing your package (we'll get into this more later) and will make supporting TypeScript and JavaScript users simultaneously much easier.
For larger projects, you'll probably prefer Jest, since it supports more advanced use cases such as snapshots. You can't as easily run Jest tests in the browser, but most UI frameworks have integrations that allow for Jest testing in Node.js.