feat: add getFilenameFromUrl to API (#911)

Author: snitin315

README.md

@@ -200,32 +200,64 @@ interact with the middleware at runtime:
 
 ### `close(callback)`
 
-Instructs a webpack-dev-middleware instance to stop watching for file changes.
+Instructs `webpack-dev-middleware` instance to stop watching for file changes.
 
-### Parameters
+#### Parameters
 
-#### callback
+##### `callback`
 
 Type: `Function`
+Required: `No`
 
 A function executed once the middleware has stopped watching.
 
-### `invalidate()`
+```js
+const express = require('express');
+const webpack = require('webpack');
+const compiler = webpack({
+  /* Webpack configuration */
+});
+const middleware = require('webpack-dev-middleware');
+const instance = middleware(compiler);
+
+const app = new express();
+
+app.use(instance);
+
+setTimeout(() => {
+  // Says `webpack` to stop watch changes
+  instance.close();
+}, 1000);
+```
 
-Instructs a webpack-dev-middleware instance to recompile the bundle.
-e.g. after a change to the configuration.
+### `invalidate(callback)`
+
+Instructs `webpack-dev-middleware` instance to recompile the bundle, e.g. after a change to the configuration.
+
+#### Parameters
+
+##### `callback`
+
+Type: `Function`
+Required: `No`
+
+A function executed once the middleware has invalidated.
 
 ```js
+const express = require('express');
 const webpack = require('webpack');
-const compiler = webpack({ ... });
+const compiler = webpack({
+  /* Webpack configuration */
+});
 const middleware = require('webpack-dev-middleware');
 const instance = middleware(compiler);
 
+const app = new express();
+
 app.use(instance);
 
 setTimeout(() => {
-  // After a short delay the configuration is changed and a banner plugin is added
-  // to the config
+  // After a short delay the configuration is changed and a banner plugin is added to the config
   new webpack.BannerPlugin('A new banner').apply(compiler);
 
   // Recompile the bundle with the banner plugin:
@@ -238,28 +270,67 @@ setTimeout(() => {
 Executes a callback function when the compiler bundle is valid, typically after
 compilation.
 
-### Parameters
+#### Parameters
 
-#### callback
+##### `callback`
 
 Type: `Function`
+Required: `No`
 
-A function executed when the bundle becomes valid. If the bundle is
-valid at the time of calling, the callback is executed immediately.
+A function executed when the bundle becomes valid.
+If the bundle is valid at the time of calling, the callback is executed immediately.
 
 ```js
+const express = require('express');
 const webpack = require('webpack');
-const compiler = webpack({ ... });
+const compiler = webpack({
+  /* Webpack configuration */
+});
 const middleware = require('webpack-dev-middleware');
 const instance = middleware(compiler);
 
+const app = new express();
+
 app.use(instance);
 
 instance.waitUntilValid(() => {
   console.log('Package is in a valid state');
 });
 ```
 
+### `getFilenameFromUrl(url)`
+
+Get filename from URL.
+
+#### Parameters
+
+##### `url`
+
+Type: `String`
+Required: `Yes`
+
+URL for the requested file.
+
+```js
+const express = require('express');
+const webpack = require('webpack');
+const compiler = webpack({
+  /* Webpack configuration */
+});
+const middleware = require('webpack-dev-middleware');
+const instance = middleware(compiler);
+
+const app = new express();
+
+app.use(instance);
+
+instance.waitUntilValid(() => {
+  const filename = instance.getFilenameFromUrl('/bundle.js');
+
+  console.log(`Filename is ${filename}`);
+});
+```
+
 ## Known Issues
 
 ### Multiple Successive Builds
@@ -289,13 +360,16 @@ process is finished with server-side rendering enabled._
 Example Implementation:
 
 ```js
+const express = require('express');
 const webpack = require('webpack');
 const compiler = webpack({
-  // webpack options
+  /* Webpack configuration */
 });
 const isObject = require('is-object');
 const middleware = require('webpack-dev-middleware');
 
+const app = new express();
+
 // This function makes server rendering of asset references consistent with different webpack chunk/entry configurations
 function normalizeAssets(assets) {
   if (isObject(assets)) {

src/index.js

@@ -2,6 +2,7 @@ import { validate } from 'schema-utils';
 import mime from 'mime-types';
 
 import middleware from './middleware';
+import getFilenameFromUrl from './utils/getFilenameFromUrl';
 import setupHooks from './utils/setupHooks';
 import setupWriteToDisk from './utils/setupWriteToDisk';
 import setupOutputFileSystem from './utils/setupOutputFileSystem';
@@ -76,17 +77,22 @@ export default function wdm(compiler, options = {}) {
   const instance = middleware(context);
 
   // API
+  instance.getFilenameFromUrl = (url) => getFilenameFromUrl(context, url);
+
   instance.waitUntilValid = (callback = noop) => {
     ready(context, callback);
   };
+
   instance.invalidate = (callback = noop) => {
     ready(context, callback);
 
     context.watching.invalidate();
   };
+
   instance.close = (callback = noop) => {
     context.watching.close(callback);
   };
+
   instance.context = context;
 
   return instance;

src/utils/getFilenameFromUrl.js

@@ -12,17 +12,18 @@ export default function getFilenameFromUrl(context, url) {
   const { options } = context;
   const paths = getPaths(context);
 
-  let filename;
+  let foundFilename;
   let urlObject;
 
   try {
     // The `url` property of the `request` is contains only  `pathname`, `search` and `hash`
     urlObject = memoizedParse(url, false, true);
   } catch (_ignoreError) {
-    return filename;
+    return;
   }
 
   for (const { publicPath, outputPath } of paths) {
+    let filename;
     let publicPathObject;
 
     try {
@@ -62,6 +63,8 @@ export default function getFilenameFromUrl(context, url) {
       }
 
       if (fsStats.isFile()) {
+        foundFilename = filename;
+
         break;
       } else if (
         fsStats.isDirectory() &&
@@ -83,11 +86,14 @@ export default function getFilenameFromUrl(context, url) {
         }
 
         if (fsStats.isFile()) {
+          foundFilename = filename;
+
           break;
         }
       }
     }
   }
 
-  return filename;
+  // eslint-disable-next-line consistent-return
+  return foundFilename;
 }