Add demo.js to npm build

To help people to get quickly started with using the package.

platform/nodejs/index.js

@@ -119,6 +119,7 @@ function pslInit(raw) {
 /******************************************************************************/
 
 function compileList({ name, raw }, compiler, writer, options = {}) {
+    if ( typeof raw !== 'string' || raw === '' ) { return; }
     const lineIter = new LineIterator(raw);
     const events = Array.isArray(options.events) ? options.events : undefined;
 

platform/npm/demo.js

@@ -0,0 +1,120 @@
+/*******************************************************************************
+ * 
+ * A simple demo to quickly get started.
+ * 
+ * Command line:
+ * 
+ *   mkdir myproject
+ *   cd myproject
+ *   npm install @gorhill/ubo-core
+ *   cp node_modules/@gorhill/ubo-core/demo.js .
+ * 
+ * There will be a `demo.js` file in your `myproject` folder, which you can
+ * modify and execute:
+ * 
+ *   node demo.js
+ * 
+ * Since the demo here uses ES module syntax, you may want to add the following
+ * to the generated package.json file to avoid the warning:
+ * 
+ *  "type": "module",
+ * 
+ * The demo will fetch filter lists from EasyList server, then serialize the
+ * content of the static network filtering engine into a local `./cache/`
+ * folder.
+ * 
+ * The serialized data will be reused if available in order to avoid fetching
+ * from remote server each time it is executed.
+ * 
+ * This demo is kept as simple as possible, so there is not a lot of error
+ * handling.
+ * 
+ * */
+
+import fs from 'fs/promises';
+import { StaticNetFilteringEngine } from '@gorhill/ubo-core';
+
+/******************************************************************************/
+
+async function main() {
+    const pathToSelfie = 'cache/selfie.txt';
+
+    const snfe = await StaticNetFilteringEngine.create();
+
+    // Up to date serialization data (aka selfie) available?
+    let selfie;
+    const ageInDays = await fs.stat(pathToSelfie).then(stat => {
+        const fileDate = new Date(stat.mtime);
+        return (Date.now() - fileDate.getTime()) / (7 * 24 * 60 * 60);
+    }).catch(( ) => Number.MAX_SAFE_INTEGER);
+
+    // Use a selfie if available and not older than 7 days
+    if ( ageInDays <= 7 ) {
+        selfie = await fs.readFile(pathToSelfie, { encoding: 'utf8' })
+            .then(data => typeof data === 'string' && data !== '' && data)
+            .catch(( ) => { });
+        if ( typeof selfie === 'string' ) {
+            await snfe.deserialize(selfie);
+        }
+    }
+
+    // Fetch filter lists if no up to date selfie available
+    if ( !selfie ) {
+        console.log(`Fetching lists...`);
+        await snfe.useLists([
+            fetch('https://easylist.to/easylist/easylist.txt')
+                .then(r => {
+                    return r.text();
+                }).then(raw => {
+                    console.log(`easylist fetched`);
+                    return { name: 'easylist', raw };
+                }).catch(reason => {
+                    console.error(reason);
+                }),
+            fetch('https://easylist.to/easylist/easyprivacy.txt')
+                .then(r => {
+                    return r.text();
+                }).then(raw => {
+                    console.log(`easyprivacy fetched`);
+                    return { name: 'easyprivacy', raw };
+                }).catch(reason => {
+                    console.error(reason);
+                }),
+        ]);
+        const selfie = await snfe.serialize();
+        await fs.mkdir('cache', { recursive: true });
+        await fs.writeFile(pathToSelfie, selfie);
+    }
+
+    // List of tests to perform
+    const tests = [
+        {
+            originURL: 'https://www.bloomberg.com/',
+            url: 'https://www.google-analytics.com/gs.js',
+            type: 'script',
+        }, {
+            originURL: 'https://www.bloomberg.com/',
+            url: 'https://securepubads.g.doubleclick.net/tag/js/gpt.js',
+            type: 'script',
+        }, {
+            originURL: 'https://www.bloomberg.com/',
+            url: 'https://bloomberg.com/main.css',
+            type: 'stylesheet',
+        }
+    ];
+
+    // Test each entry for a match against the content of the engine
+    for ( const test of tests ) {
+        console.log('\nRequest details:', test);
+        const r = snfe.matchRequest(test);
+        if ( r === 1 ) { // Blocked
+            console.log('Blocked:', snfe.toLogData());
+        } else if ( r === 2 ) { // Unblocked
+            console.log('Unblocked:', snfe.toLogData());
+        } else { // Not blocked
+            console.log('Not blocked');
+        }
+    }
+}
+
+main();