Change NotifyOnChangeOnly to accept a list

README.md

@@ -47,7 +47,7 @@ You can provide additional parameters to constructor:
 - `userAgent` - by default `icecast-parser`.
 - `keepListen` - by default `false`. If you set to `true`, then response from radio station will not be destroyed and you can pipe it to another streams. E.g. piping it to the `speaker` module.
 - `autoUpdate` - by default `true`. If you set to `false`, then parser will not be listening for recent updates and immediately close the stream. So that, you will get a metadata only once.
-- `notifyOnChangeOnly` - by default `false`. If you set both `autoUpdate` and `notifyOnChangeOnly` to `true`, it will keep listening the stream and notifying you about metadata, but it will not notify if metadata did not change from the previous time.
+- `notifyOnChangeOnly` - by default `[]`. If you set both `autoUpdate` to `true` and `notifyOnChangeOnly` to include the a list of metadata keys to listen for (`['StreamTitle', 'StreamUrl']`), it will keep listening the stream and notifying you about metadata, but it will not notify if the selected metadata did not change from the previous time.
 - `errorInterval` - by default 10 minutes. If an error occurred when requesting, the next try will be executed after this interval. Works only if `autoUpdate` is enabled.
 - `emptyInterval` - by default 5 minutes. If the request was fullfiled but the metadata field was empty, the next try will be executed after this interval. Works only if `autoUpdate` is enabled.
 - `metadataInterval` - by default 5 seconds. If the request was fullfiled and the metadata was present, the next update will be scheduled after this interval. Works only if `autoUpdate` is enabled.
@@ -61,7 +61,7 @@ const radioStation = new Parser({
   errorInterval: 10 * 60,
   keepListen: false,
   metadataInterval: 5,
-  notifyOnChangeOnly: false,
+  notifyOnChangeOnly: [],
   url: 'https://live.hunter.fm/80s_high',
   userAgent: 'Custom User Agent',
 });

package.json

@@ -1,6 +1,6 @@
 {
   "name": "icecast-parser",
-  "version": "4.0.2",
+  "version": "4.0.3",
   "description": "Node.js module for getting and parsing metadata from SHOUTcast/Icecast radio streams",
   "main": "dist/Parser.js",
   "license": "MIT",

src/Parser.ts

@@ -9,7 +9,7 @@ export interface ParserOptions {
   errorInterval: number
   keepListen: boolean
   metadataInterval: number
-  notifyOnChangeOnly: boolean
+  notifyOnChangeOnly: string[]
   url: string
   userAgent: string
 }
@@ -35,7 +35,7 @@ export class Parser extends EventEmitter {
     errorInterval: 10 * 60,
     keepListen: false,
     metadataInterval: 5,
-    notifyOnChangeOnly: false,
+    notifyOnChangeOnly: [],
     url: '',
     userAgent: 'icecast-parser',
   };
@@ -115,12 +115,22 @@ export class Parser extends EventEmitter {
   }
 
   protected isMetadataChanged (metadata: Map<string, string>): boolean {
-    for (const [key, value] of metadata.entries()) {
-      if (this.previousMetadata.get(key) !== value) {
-        return true;
+    if (this.options.notifyOnChangeOnly.length > 0) {
+      for (const key of this.options.notifyOnChangeOnly) {
+        const data = metadata.get(key)
+        if (data) {
+          if (this.previousMetadata.get(key) !== data) {
+            return true;
+          }
+        }
       }
+    } else {
+      for (const [key, value] of metadata.entries()) {
+        if (this.previousMetadata.get(key) !== value) {
+          return true;
+        }
+      }      
     }
-
     return false;
   }
 }

test/Parser.spec.ts

@@ -57,11 +57,40 @@ describe('parser', () => {
   it('should properly emit metadata event when metadata has been updated', async () => await new Promise((resolve) => {
     expect.hasAssertions();
 
-    const radio = new Parser({ autoUpdate: false, notifyOnChangeOnly: true, url: 'https://live.hunter.fm/80s_high' });
+    const radio = new Parser({ autoUpdate: false, notifyOnChangeOnly: [], url: 'https://live.hunter.fm/80s_high' });
     radio.on('metadata', (metadata) => {
       // @ts-expect-error I want to check that metadata was stored in the private property to later comparsion
       expect(radio.previousMetadata).toStrictEqual(metadata);
       resolve();
     });
   }));
+
+  it('should properly emit metadata event when notifyOnChangeOnly is used and when metadata has been updated', async () => await new Promise((resolve) => {
+    expect.hasAssertions()
+
+    const radio = new Parser({ autoUpdate: false, notifyOnChangeOnly: ['StreamTitle'], url: 'https://live.hunter.fm/80s_high' });
+    radio.on('metadata', (metadata) => {
+      // @ts-expect-error I want to check that metadata was stored in the private property to later comparsion
+      expect(radio.previousMetadata).toStrictEqual(metadata);
+      resolve();
+    });
+  }))
+
+  it('should not emmit metadata event if notifyOnChangeOnly is incorrect', async () => await new Promise(async (resolve) => {
+    let triggered = false
+    const delay = (ms: number) => new Promise(res => setTimeout(res, ms));
+
+    const radio = new Parser({ autoUpdate: false, notifyOnChangeOnly: ['a'], url: 'https://live.hunter.fm/80s_high' });
+    radio.on('metadata', () => {
+      triggered = true
+    });
+
+    await delay(1000)
+
+    if(!triggered) {
+      resolve()
+    } else {
+      throw new Error('metadata event was triggered - Check that the notifyOnChangeOnly data does not exist in the metadata')
+    }
+  }))
 });