solarliner/preact-cli-experiment

Experiments on a Preact CLI with proper modularity

⚛️ Preact CLI (Experiment)

New CLI for Preact featuring a plugin-based system

Install

This project is a monorepo and uses yarn and lerna to manage internal and external dependencies.

yarn lerna bootstrap

Run

Note: As it is in its early stages, running the CLI only works in Unix-style environments. Windows users, use MSYS or WSL.

You can run a development version (without transpiling) of the CLI by going to packages/cli and running yarn dev.

cd packages/cli
yarn dev [options] <command> [options]
# Example
yarn dev --cwd /tmp/ new preact-app # Creates a project in a folder called "preact-app", working in the temp directory

Reference guide

The CLI resolves any installed plugins at startup, and hooks into exported functions for them to tap into the CLI. With plugins, you can create new commands, mutate the webpack configuration (uses webpack-chain), and even create new functionality by invoking other plugins' exported functions.

You can take a look at how the new command is built as an internal plugin, and how the build command hooks into other plugins to mutate the webpack configuration.

The Plugin API

Each exported function from a plugin, when called, is passed a PluginAPI instance it can use to interact with the CLI. Each exported function is used with the following signature:

/**
 * Hooks into the Preact CLI.
 * @param api API instance for the plugin
 * @param opts Options for the hook, contains the global CLI options, can contain more depending on the hook
 * @return Value defined and used depending on the hook.
 */
function hook(api: PluginAPI, opts: CLIArguments /* Can also include more properties depending on the hook */): any {}

List of available hooks

cli

Gets called on CLI startup.

function cli(api: PluginAPI, opts: CLIArguments): void {}

build

Gets called at the start of the build step.s

interface BuildArgv {
	analyze: boolean;
	brotli: boolean;
	clean: boolean;
	dest: string;
	esm: boolean;
	inlineCss: boolean;
	prerender: boolean;
	preload: boolean;
	production: boolean;
	sw: boolean;
	template?: string;
}

function build(api: PluginAPI, opts: CLIArguments & BuildArgv): void;

PluginAPI instance

The Plugin API object is a class instance that's shared between hooks, though a shared state cannot be saved there.

setStatus(text?: string, type?: "info" | "error" | "fatal" | "success")

Prints to terminal the current status of the process. This is used for end-user logging. Proper feedback is important, as otherwise the user might think the CLI is stuck, and will abort it early. Internally, Preact CLI uses ora to show an animated spinner.

When called without arguments, this stops and removes the spinner, persisting the last message into stderr. When called with one argument, the new status text, the spinner updates its status text. When called with two arguments, a logging text and a type identifier, the spinner persists the input text prefixed with an icon corresponding to the type.

Examples:

api.setStatus("Status"); // @preact/cli:plugin:foo [/] Status
api.setStatus(); // @preact/cli:plugin:foo  Status
api.setStatus("Working..."); // @preact/cli:plugin:foo [/] Working...
api.setStatus("Creation complete", "success"); // @preact/cli:plugin:foo ✔️ Creaction complete \n @preact/cli:plugin:foo [/] Working...
api.setStatus("FATAL ERROR", "fatal"); // @preact/cli:plugin:foo ❌ FATAL ERROR [program exists with code 1]

registerCommand(name: string, options?: CommandOptions): Command

Registers a new command to add to the CLI. This returns a Command object from te commander package allowing you to personalize the command, add options, and set an action callback.

Example: The new command

chainWebpack(chainer: WebpackChainer)

type WebpackChainer = (config: webpackChain.Config) => void;

Adds a transformer function for the webpack configuration.

The function doesn't get called immediately; rather all transformer functions are collected and applied during the build step.

Example:

// Add a minifier plugin
api.chainWebpack(config => config.plugin("terser").use(TerserPlugin, [terserOptions]));

async applyTemplate(fileOrFolder: string, context: Record<string, string>, base?: string): Promise<Record<string, string>>

Renders a file or folder template into the project. Returns an object with relative filenames as keys, and file contents as values, to be passed to writeFileTree to write to disk.

• fileOrFolder is the file or folder to render; is relative to base or absolute.
• context is an object containing template variables as keys and their content as values. This context gets merged with a default context which contains the environment variables as €nv and the current working directory as cwd.
• base is the base folder - it maps to the project folder. All output files are applied form this base folder into the project root. When unspecified, it is the project directory.

Example:

See The build command for an example of plugin using applyTemplate.

async writeFileTree(files: Record<string, string>, base?: string)

Writes the given object to disk, relative to base.

• files is a dictionary of relative path keys and content values (like the object returned by applyTemplate) to write to disk.
• base is the base directory from which all relatives files are mapped to. If unspecified, it is the project directory. If relative, it is relative to the project directory.

Example

const project = {
	"package.json" : JSON.stringify(pkg, null, 2),
	"README.md": generateReadme();
	"src/index.js": createEntrypoint({name: "foobar"})
};
api.writeFileTree(project);

const sources = {
	"routes/index.jsx": createRoute("index"),
	"routes/profile/index.jsx": createRoute("profile", "developit"),
	"routes/prodile/solarliner.jsx": createRoute("profile", "solarliner")
}
api.writeFileTree(files, "src");

getChains(): WebpackChainer[]

WARNING: Internal function.

Returns an array of all defined webpack-chain transform functions by the plugin.