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Version: v4.20

Integrated Dev Server

Stencil comes with an integrated dev server in order to simplify development. By integrating the build process and the dev server, Stencil is able to drastically improve the development experience without requiring complicated build scripts and configuration. As app builds and re-builds take place, the compiler is able to communicate with the dev server, and vice versa.

Hot Module Replacement​

The compiler already provides a watch mode, but coupled with the dev server it's able to go one step farther by reloading only what has changed within the browser. Hot Module Replacement allows the app to keep its state within the browser, while switching out individual components with their updated logic after file saves.

Style Replacement​

Web components can come with their own css, can use shadow dom, and can have individual style tags. Traditionally, live-reload external css links usually does the trick, however, updating components with inline styles within shadow roots has been a challenge. With the integrated dev server, Stencil is able to dynamically update styles for all components, whether they're using shadow dom or not, without requiring a page refresh.

Development Errors​

When errors happen during development, such as printing an error for invalid syntax, Stencil will not only log the error and the source of the error in the console, but also overlay the app with the error so it's easier to read.

Open In Editor​

When a development error is shown and overlays the project within the browser, line numbers pointing to the source text are clickable, which will open the source file directly in your IDE.

Dev Server Config​

address​

Optional

Type: string

Default: 0.0.0.0

IP address used by the dev server. The default is 0.0.0.0, which points to all IPv4 addresses on the local machine, such as localhost.

basePath​

Optional

Type: string

Default: /

Base path to be used by the server. Defaults to the root pathname.

https​

Optional

Type: { key: string; cert: string; } | false

Default: false

By default the dev server runs over the http protocol. Instead you can run it over https by providing your own SSL certificate and key (see example below).

Example​

import { readFileSync } from 'fs';
import { Config } from '@stencil/core';

export const config: Config = {
  devServer: {
    reloadStrategy: 'pageReload',
    port: 4444,
    https: {
      cert: readFileSync('cert.pem', 'utf8'),
      key: readFileSync('key.pem', 'utf8'),
    },
  },
};

initialLoadUrl​

Optional

Type: string

Default: /

The URL the dev server should first open to.

logRequests​

Optional

Type: boolean

Default: false

Every request to the server will be logged within the terminal.

openBrowser​

Optional

Type: boolean

Default: true

By default, when dev server is started the local dev URL is opened in your default browser. However, to prevent this URL to be opened change this value to false.

pingRoute​

Optional

Type: string | null

Default: /ping

Route to be registered on the dev server that will respond with a 200 OK response once the Stencil build has completed. The Stencil dev server will "spin up" before the build process has completed, which can cause issues with processes that rely on the compiled and served output (like E2E testing). This route provides a way for these processes to know when the build has finished and is ready to be accessed.

If set to null, no route will be registered.

port​

Optional

Type: number

Default: 3333

Sets the server's port.

reloadStrategy​

Optional

Type: 'hmr' | 'pageReload' | null

Default: hmr

When files are watched and updated, by default the dev server will use hmr (Hot Module Replacement) to update the page without a full page refresh. To have the page do a full refresh use pageReload. To disable any reloading, use null.

root​

Optional

Type: string

Default: www output directory if exists, project root otherwise

The directory to serve files from.

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