LWC Uplift Toolkit

Getting started

To make the toolkit available on your developer machine, run the following in a directory of your choosing.

git clone [email protected]:dbustad/lwc-uplift-toolkit.git
cd lwc-uplift-toolkit
npm install && npm link

Once this project reaches maturity, this package will likely be published to public NPM. At that point, this Getting Started section will be made obsolete, and you'll be able to skip ahead to the npx invocation described the section below.

In the future, you'll be able to add @lwc/uplift-toolkit to your devDependencies and invoke the command in package.json NPM scripts.

Basic usage

Playground

In your terminal, navigate to the root directory of your project where your lwc.config.json is located. If you're using the lwc field in package.json, you should run the playground from the same directory as your package.json.

Run the playground like so:

npx -p @lwc/uplift-toolkit playground COMPONENT_SPECIFIER

You can optionally pass an --open flag to open your default browser automatically.

COMPONENT_SPECIFIER should be of form namespace/name or namespace-name. For example, in the example directory of this project, you might run npx -p @lwc/uplift-toolkit playground x/parent.

If the "re-render when code is updated" checkbox is enabled in the playground Config, the component will be re-rendered automatically.

Test Runner

Similarly to the playground, the test runner should be run from the same directory as lwc.config.json or package.json. It is invoked like so:

npx -p @lwc/uplift-toolkit test-lwcs SPEC_FILE_PATTERN

You may want to surround your SPEC_FILE_PATTERN in single quotes, depending on whether your shell automatically expands glob patterns (ZSH, for example).

To distinguish SSR-related tests from existing Jest tests, you will likely want each type of test to have its own distinct file extension. For example, if your Jest tests are named COMPONENT_NAME.spec.js, you may want to name your SSR-related test file COMPONENT_NAME.spec.ssr.js. If you did so, the command to run your tests might be:

npm -p @lwc/uplift-toolkit test-lwcs './src/**/*.spec.ssr.js';

The available utilities within tests are very much in flux at this time, so there is no extensive documentation. However, there are four imports that are likely to get heavy use in your SSR-related tests:

import {
  expect,
  renderToMarkup,
  insertMarkupIntoDom,
  hydrateElement,
} from '@lwc/uplift-toolkit/test.js';

• expect comes from the Chai assertion library, and has some DOM- and Web Component- related plugins preinstalled.
• renderToMarkup is an async function that takes the path to your component and the props that should be used for rendering. It returns Promise<String> where the String is HTML markup.
• insertMarkupIntoDom is an async function that takes SSR markup (like that returned from renderToMarkup) as its singe argument. It returns Promise<HtmlElement>, which is a handle to the root element of your SSR-rendered DOM subtree.
• hydrateElement is an async function that takes a root el (like that returned from insertMarkupIntoDom) and component props (which should probably be the same as what was passed to renderToMarkup). It a Promise<Boolean>, where the Boolean indicates whether hydration completed without validation errors. In most cases, you'll want this Boolean value to be true.

Playground configuration

By default, the uplift playground will take your component through the three stages of its SSR lifecycle:

• rendering the component to HTML markup on the server
• inserting that markup into the DOM on the client
• hydrating the DOM subtree and associating it with an instance of your component class

As you work through the various scenarios you'd like your component to support in SSR, a handful of tools are available to you:

• You can prevent the playground from rehydrating SSR markup after it has been inserted into the DOM.
• Alternately, you can prevent the playground from inserting SSR markup into the DOM altogether.
• If your browser dev tools are open, you can pause execution of JavaScript prior to any/all of the three SSR lifecycle stages.

Component Props

In many cases, you'll want to explore the functionality of your component by changing its props. Any fields that are decorated with @api will be displayed in the playground Config section. To set the prop during rendering, toggle the "enabled" button and click on <unset> to enter a JavaScript expression.

The props don't have to be strings, and they don't even have to be serializable JavaScript objects. Any JavaScript expression that could be evaluated in an SSR enviroment should be supported. Take for example the following component:

import { LightningElement } from 'lwc';
export default class HelloWorld extends LightningElement {
	@api foo;
	@api bar = 'default value';
	baz = 'internal';
}

In the playground, you'd see configuration options for two props: foo and bar. If you didn't override the values using the playground configuration, the rendered instance of HelloWorld would have a value of undefined for foo and "default value" for bar. However, you could provide the following as the config for foo in the playground config:

{
	// my foo object
	"fooChild": new Date(),
}

When renderd, this.foo (or foo in the corresponding template) would be an object with property fooChild set to a Date object.

These prop values will persist when "re-render when code is updated" is enabled and you make change to your component code.