only connect via osc when .osc is called

packages/osc/osc.mjs

@@ -5,10 +5,35 @@ This program is free software: you can redistribute it and/or modify it under th
 */
 
 import OSC from 'osc-js';
-import { parseNumeral, Pattern } from '@strudel.cycles/core';
+import { logger, parseNumeral, Pattern } from '@strudel.cycles/core';
+
+let connection; // Promise<OSC>
+function connect() {
+  if (!connection) {
+    // make sure this runs only once
+    connection = new Promise((resolve, reject) => {
+      const osc = new OSC();
+      osc.open();
+      osc.on('open', () => {
+        logger('OSC connected!');
+        resolve(osc);
+      });
+      osc.on('close', () => {
+        connection = undefined; // allows new connection afterwards
+        console.log('osc connection closed');
+        reject('OSC connection closed');
+      });
+      osc.on('error', (err) => reject(err));
+    }).catch((err) => {
+      connection = undefined;
+      throw new Error('Could not connect to OSC server. Is it running?');
+    });
+  } else {
+    console.log('already has connection');
+  }
+  return connection;
+}
 
-const comm = new OSC();
-comm.open();
 const latency = 0.1;
 let startedAt = -1;
 
@@ -20,9 +45,10 @@ let startedAt = -1;
  * @memberof Pattern
  * @returns Pattern
  */
-Pattern.prototype.osc = function () {
+Pattern.prototype.osc = async function () {
+  const osc = await connect();
   return this._withHap((hap) => {
-    const onTrigger = (time, hap, currentTime, cps) => {
+    const onTrigger = (time, hap, currentTime, cps = 1) => {
       const cycle = hap.wholeOrPart().begin.valueOf();
       const delta = hap.duration.valueOf();
       // time should be audio time of onset
@@ -34,13 +60,12 @@ Pattern.prototype.osc = function () {
       // make sure n and note are numbers
       controls.n && (controls.n = parseNumeral(controls.n));
       controls.note && (controls.note = parseNumeral(controls.note));
-
       const keyvals = Object.entries(controls).flat();
       const ts = Math.floor(startedAt + (time + latency) * 1000);
       const message = new OSC.Message('/dirt/play', ...keyvals);
       const bundle = new OSC.Bundle([message], ts);
       bundle.timestamp(ts); // workaround for https://github.com/adzialocha/osc-js/issues/60
-      comm.send(bundle);
+      osc.send(bundle);
     };
     return hap.setContext({ ...hap.context, onTrigger });
   });