dvlp is a no-configuration, no-conditionals, no-middleware, no-nonsense (no-vowels!) dev server toolkit to help you develop quickly and easily for the web. You shouldn't have to jump through hoops to get a development environment up and running, and you definitely shouldn't have to include development-only stuff in your high-quality production code! dvlp is full of hacks so your code doesn't have to be!
- No bundling: write JS modules and load them directly in the browser
- No middleware: write application servers without special dev/build/bundle middleware
- No infrastructure: mock external JSON/EventSource/WebSocket resources
- No waiting: restart application servers in the blink of an eye
- No refreshing: automatically reload clients on file change
dvlp allows you to easily serve resources from one or more project directories (static mode), from your custom application server (app mode), or from your Electron desktop application (electron mode). In all cases, dvlp creates a proxy server in front of your content, automatically injecting the necessary reload script into HTML responses to enable reloading, and watches all files for changes, restarts the app server/ electron application if necessary, and reloads all connected clients.
In addition, when working with JS modules, dvlp will ensure that so-called bare imports (import "lodash"), which are not natively supported by browsers, work by re-writing all import paths to valid urls. Since some node_modules packages are still published as CommonJS modules, non-ESM packages are bundled and converted to an ESM module using esbuild. These bundles are versioned and cached for efficient reuse in the .dvlp directory under your project root.
dvlp also includes a testServer for handling various network request scenarios (mocking, latency, errors, offline, etc.) during testing.
Install globally or locally in your project with npm/yarn:
$ npm install dvlpUsage: dvlp [options] [path...]
Start a development server, restarting and reloading connected clients on file changes.
Serves static files from one or more "path" directories, or a custom application
server if "path" is a single application server file.
Options:
-p, --port <port> port number
-m, --mock <path> path to mock files (directory, file, glob pattern)
-k, --hooks <path> path to optional hooks registration file
-e, --electron run "path" file as electron.js entry file
--ssl <path> enable https mode by specifying path to directory containing ".crt" and ".key" files (directory,
glob pattern)
-s, --silent suppress all logging
--verbose enable verbose logging
--no-reload disable reloading connected clients on file change
-v, --version output the current version
-h, --help display help for command
Add a script to your package.json scripts:
{
"scripts": {
"dev": "dvlp --port 8000 src/app.js"
}
}...and launch:
$ npm run dev
In some cases, source code may need to be transformed into a valid format before it is executed, or a response body modified before sending it to the browser. In these cases, you can register hooks to convert file contents on the fly when imported by an application server or requested by the browser.
Registering hooks
Create a Node.js module that exposes one or more supported lifecycle hook functions:
// scripts/hooks.js
import sass from 'sass';
const RE_SASS = /\.s[ac]ss$/;
export default {
/**
* Bundle non-esm node_modules dependency requested by the browser.
* This hook is run after file read.
*
* @param { string } id
* @param { string } filePath
* @param { string } fileContents
* @param { { esbuild: Pick<import("esbuild"), 'build'> } } context
*/
async onDependencyBundle(id, filePath, fileContents, context) {
if (id === 'some/package') {
// Transform
}
}
/**
* Transform file contents for file requested by the browser.
* This hook is run after file read, and before any modifications by dvlp.
*
* @param { string } filePath
* @param { string } fileContents
* @param { { client: { manufacturer: string, name: string, ua: string, version: string }, esbuild: Pick<import("esbuild"), 'build', 'transform'> } } context
*/
async onTransform(filePath, fileContents, context) {
// Note: .ts, .tsx, .jsx files are transformed by default
if (RE_SASS.test(filePath)) {
return sass.renderSync({
file: filePath,
}).css;
}
},
/**
* Manually resolve import specifier.
* This hook is run for each import statement.
* If returns "false", import re-writing is skipped.
* If returns "undefined", import specifier is re-written using default resolver.
* If "context.isDynamic", also possible to return replacement for whole expression.
*
* @param { string } specifier
* @param { { importer: string, isDynamic: boolean } } context
* @param { (specifier: string, importer: string) => string | undefined } defaultResolve
*/
onResolveImport(specifier, context, defaultResolve) {
if (context.isDynamic) {
return `dynamicImport('./some-path-prefix/${specifier}.js', '${context.importer}')`;
}
},
/**
* Manually handle response for incoming server request.
* If returns "true", further processing by dvlp will be aborted.
*
* @param { IncomingMessage | Http2ServerRequest } request
* @param { ServerResponse | Http2ServerResponse } response
* @returns { Promise<boolean> | boolean | undefined }
*/
onRequest(request, response) {
if (request.url === '/something') {
response.writeHead(200);
response.end('handled');
return true;
}
},
/**
* Modify response body before sending to the browser.
* This hook is run after all modifications by dvlp, and before sending to the browser.
*
* @param { string } filePath
* @param { string } responseBody
*/
onSend(filePath, responseBody) {
if (RE_JS.test(filePath)) {
return responseBody.replace('__VERSION__', '1.0.0');
}
},
/**
* Transform file contents for application server.
*
* @param { string } filePath
* @param { { format?: string } } context
* @param { NodeLoadLoaderHook } defaultTransform
* @returns { { format: string; source: string | SharedArrayBuffer | Uint8Array } }
*/
onServerTransform(filePath, context, defaultTransform) {
// Note: .ts, .tsx, .jsx files are transformed by default
// @see https://nodejs.org/api/esm.html#loadurl-context-defaultload
},
/**
* Manually resolve import specifiers for application server.
*
* @param { string } specifier
* @param { { conditions: Array<string>; parentURL?: string } } context
* @param { NodeResolveLoaderHook } defaultResolve
* @returns { { format?: string; url: string } }
*/
onServerResolve(specifier, context, defaultResolve){
// @see https://nodejs.org/api/esm.html#resolvespecifier-context-defaultresolve
}
};...reference the original file as you normally would:
<link rel="stylesheet" href="src/index.sass" />...and pass a reference to the hooks.js file with the -k, --hooks option:
{
"scripts": {
"dev": "dvlp --hooks scripts/hooks.js --port 8000 src/app.js"
}
}When developing locally, it's often useful to mock responses for requests made by your server or browser application, especially when working with an external API. dvlp lets you quickly and easily mock endpoints by intercepting requests that match those registered with the -m, --mock option.
Mocking request/response
Mock a response by creating a .json file describing the mocked request/response:
{
"request": {
"url": "http://www.someapi.com/v1/id/101010",
"ignoreSearch": true
},
"response": {
"headers": {
"x-custom": "custom header"
},
"body": {
"user": {
"name": "Nancy",
"id": "101010"
}
}
}
}(Setting request.ignoreSearch = true will ignore query parameters when matching an incoming request with the mocked response)
Bad responses can also be mocked by setting hang, error, missing, or offline response properties:
{
"request": {
"url": "http://www.someapi.com/v1/id/101010"
},
"response": {
"error": true,
"body": {}
}
}Multiple mocked responses may also be included in a single file:
[
{
"request": {
"url": "http://www.someapi.com/v1/id/101010"
},
"response": {
"body": {}
}
},
{
"request": {
"url": "http://www.someapi.com/v1/id/202020"
},
"response": {
"body": {}
}
}
]Though JSON responses are probably the most common, it's also possible to mock other types of payloads by linking the response.body to an external file:
{
"request": {
"url": "http://www.someplace.com/images/avatar.jpg"
},
"response": {
"body": "../assets/avatar.jpg"
}
}(File paths referenced in response.body are relative to the mock file, not the web/project root)
Register mocked responses with the command-line option -m, --mock and a path to your mock files:
{
"scripts": {
"dev": "dvlp --mock path/to/mock/files --port 8000 src/app.js"
}
}Your path/to/mock/files could be one of the following:
- path to directory of files:
path/to/mock/directory - path to a single file:
path/to/mock.json
(The following require wrapping in "")
- globbed path to multiple files/directories:
"path/to/mock/{api,assets}" - multiple files/directories separated by space,
,,:, or;:"path/to/mock1.json, path/to/mock2.json"
Mocking stream/events
Mock a WebSocket or EventStream by creating a .json file describing the mocked stream/events:
{
"stream": {
"url": "ws://www.somesocket.com/stream",
"ignoreSearch": true,
"protocol": "socket.io"
},
"events": [
{
"name": "hello Bob",
"connect": true,
"message": {
"people": ["Bob Builder"]
},
"options": {
"event": "update",
"namespace": "/people"
}
},
{
"name": "hello Ernie",
"message": {
"people": ["Bob Builder", "Ernie Engineer"]
},
"options": {
"event": "update",
"namespace": "/people"
}
}
]
}(Setting request.ignoreSearch = true will ignore query parameters when matching an incoming request with the mocked response)
(Specifying a stream.protocol = "socket.io" will negotiate WebSocket responses using the Socket.io protocol)
An event's name is a custom, unique string used to identify the event for manual triggering (see below). Adding the property connect: true will flag an event to be triggered automatically on initial connection.
A sequence of events may also be described by nesting events under the sequence property:
{
"stream": {
"url": "http://www.someeventsource.com/stream"
},
"events": [
{
"name": "a sequence of unfortunate events",
"sequence": [
{
"message": "oh",
"options": {
"event": "update"
}
},
{
"message": "no",
"options": {
"event": "update",
"delay": 100
}
},
{
"message": "not",
"options": {
"event": "update",
"delay": 50
}
},
{
"message": "again!",
"options": {
"event": "update",
"delay": 10
}
}
]
}
]
}Register mocked responses with the command-line option -m, --mock and a path to your mock files:
{
"scripts": {
"dev": "dvlp --mock path/to/mock/files --port 8000 src/app.js"
}
}Your path/to/mock/files could be one of the following:
- path to directory of files:
path/to/mock/directory - path to a single file:
path/to/mock.json
(Note that the following require wrapping in "")
- globbed path to multiple files/directories:
"path/to/mock/{api,assets}" - multiple files/directories separated by space,
,, or;:"path/to/mock1.json, path/to/mock2.json"
Triggering mocked stream events
Once registered, mocked stream events may be triggerd from your browser's console:
dvlp.pushEvent('ws://www.somesocket.com/stream', 'hello Ernie');Mocking in the browser
All mocks registered with the -m, --mock option are also enabled by default in the browser. In addition, similar to the testServer, you can register mocks programatically:
import { testBrowser } from 'dvlp/test-browser';
describe('some test', () => {
before(() => {
testBrowser.disableNetwork();
});
after(() => {
testBrowser.enableNetwork();
});
it('should fetch mock data', async () => {
const href = 'https://www.google.com';
testBrowser.mockResponse(
href,
(req, res) => {
res.writeHead(500);
res.end('error');
},
true,
);
const res = await fetch(href);
assert.equal(res.status, 500);
});
});As mentioned in How it works, dvlp will bundle CommonJS packages imported from node_modules in order to convert them to es6 modules. esbuild is used to create these bundles, and they are then cached on disk inside the .dvlp directory under your project root.
In the (rare) case you need to customise bundling to work with the packages you're importing, you can register a onDependencyBundle hook.
Enable development against a secure http2 server by passing the path or glob pattern to your .crt and .key files with the --ssl option.
Follow the directions here to generate a self-signed certificate for local development
dvlp uses the debug.js debugging utility internally. Set the following environment variable before running to see detailed debug messages:
$ DEBUG=dvlp* npm run dev
Serve files at filePath, starting static file server if one or more directories, or app server if a single file or function (which starts an application server when imported/called).
options include:
certsPath: string|[string]: the path or glob pattern containing ".crt" and ".key" files (default'')directories: [string]: additional directories to use for resolving file requests (default[])hooksPath: string: the path to a hooks registration file (default'')mockPath: string|[string]the path(s) to load mock files from (default'')port: number: port to expose onlocalhost. Will useprocess.env.PORTif not specified here (default8080)reload: boolean: enable/disable browser reloading (defaulttrue)silent: boolean: disable/enable default logging (defaultfalse)
import { server } from 'dvlp';
const appServer = await server('path/to/app.js', { port: 8080 });Create a server for handling network requests during testing.
options include:
autorespond: booleanenable/disable automatic dummy responses. If unable to resolve a request to a local file or mock, the server will respond with a dummy response of the appropriate type (defaultfalse)latency: numberthe amount of artificial latency to introduce (inms) for responses (default50)port: numberthe port to expose onlocalhost. Will useprocess.env.PORTif not specified here (default8080)webroot: Stringthe subpath fromprocess.cwd()to prepend to relative paths (default'')
import { testServer } from 'dvlp/test';
const mockApi = await testServer({ port: 8080, latency: 20, webroot: 'src' });Returns a TestServer instance with the following methods:
loadMockFiles(filePath: string|[string]): voidload and register mock response files (see mocking)
{
"request": {
"url": "http://www.someapi.com/v1/id/101010"
},
"response": {
"body": {
"user": {
"name": "Nancy",
"id": "101010"
}
}
}
}mockApi.loadMockFiles('path/to/mock/101010.json');
const res = await fetch('http://www.someapi.com/v1/id/101010');
console.log(await res.json()); // => { user: { name: "nancy", id: "101010" } }mockResponse(request: string|object, response: object|(req, res) => void, once: boolean, onMockCallback: () => void): () => voidadd a mockresponseforrequest, optionally removing it after first use, and/or triggering a callback when successfully mocked (see mocking). Returns a function that may be called to remove the added mock at any time.
mockApi.mockResponse(
'/api/user/1234',
{
body: {
id: '1234',
name: 'bob',
},
},
true,
);
const res = await fetch('http://localhost:8080/api/user/1234');
console.log(await res.json()); // => { id: "1234", name: "bob" }Or pass a response handler:
const removeMock = mockApi.mockResponse(
'/api/user/1234',
(req, res) => {
res.writeHead(200, {
'Content-Type': 'application/json',
});
res.end(JSON.stringify({ id: '1234', name: 'bob' }));
},
true,
);
const res = await fetch('http://localhost:8080/api/user/1234');
console.log(await res.json()); // => { id: "1234", name: "bob" }
removeMock();mockPushEvents(stream: string|object, events: object|[object]): () => voidadd one or more mockeventsfor a WebSocket/EventSourcestream(see mocking). Returns a function that may be called to remove the added mock at any time.
const removeMock = mockApi.mockPushEvents('ws://www.somesocket.com/stream', [
{
name: 'hi',
message: 'hi!',
},
{
name: 'so scary',
message: 'boo!',
},
]);
ws = new WebSocket('ws://www.somesocket.com/stream');
ws.addEventListener('message', (event) => {
console.log(event.data); // => hi!
removeMock();
});pushEvent(stream: string|object, event: string|object’):voidpush data to WebSocket/EventSource clients. A string passed as 'event' will be handled as a named mock push event (see mocking)
mockApi.pushEvent('ws://www.somesocket.com/stream', 'so scary');-
ref(): voidprevent process from exiting while this server is active -
unref(): voidallow process to exit if this is the only active -
destroy(): Promise<void>stop and clean up running server
In addition, testServer supports the following special query parameters:
offlinesimulate an offline state by terminating the request (fetch('http://localhost:3333/foo.js?offline'))errorreturn a 500 server error response (fetch('http://localhost:3333/foo.js?error'))missingreturn a 404 not found response (fetch('http://localhost:3333/foo.js?missing'))maxage=valueconfigureCache-Control: public, max-age={value}cache header (fetch('http://localhost:3333/foo.js?maxage=10'))hanghold connection open without responding (fetch('http://localhost:3333/foo.js?hang'))
Disable all network requests with origin that is not localhost. Prevents all external network requests for the current Node.js process. If rerouteAllRequests is set to true, all external requests will be re-routed to the current running server.
testServer.disableNetwork();
await fetch('https://github.com/popeindustries/dvlp');
// => Error "network connections disabled"Re-enables all previously disabled external network requests for the current Node.js process.
- testBrowser.mockResponse(request: string|object, response: object|(req, res) => void, once: boolean, onMockCallback: () => void): () => void
Add a mock response for request, optionally removing it after first use, and/or triggering a callback when successfully mocked (see mocking). Returns a function that may be called to remove the added mock at any time.
// Also available as "window.dvlp"
import { testBrowser } from 'dvlp/test-browser';
testBrowser.mockResponse(
'http://localhost:8080/api/user/1234',
{
body: {
id: '1234',
name: 'bob',
},
},
true,
);Push data to WebSocket/EventSource clients. A string passed as 'event' will be handled as a named mock push event (see mocking).
testBrowser.pushEvent('ws://www.somesocket.com/stream', 'so scary');Disable all network requests with origin that is not localhost. Prevents all external AJAX/Fetch/EventSource/WebSocket requests originating from the current browser window. If rerouteAllRequests is set to true, all external requests will be re-routed to the running dvlp service.
testBrowser.disableNetwork();
await fetch('https://github.com/popeindustries/dvlp');
// => Error "network connections disabled"Re-enables all previously disabled requests originating from the current browser window.