build

docs/_snowpack/link/util.js

@@ -0,0 +1,33 @@
+export const isNote = (name) => /^[a-gA-G][#b]*[0-9]$/.test(name);
+export const tokenizeNote = (note) => {
+  if (typeof note !== "string") {
+    return [];
+  }
+  const [pc, acc = "", oct] = note.match(/^([a-gA-G])([#b]*)([0-9])?$/)?.slice(1) || [];
+  if (!pc) {
+    return [];
+  }
+  return [pc, acc, oct ? Number(oct) : void 0];
+};
+export const toMidi = (note) => {
+  const [pc, acc, oct] = tokenizeNote(note);
+  if (!pc) {
+    throw new Error('not a note: "' + note + '"');
+  }
+  const chroma = {c: 0, d: 2, e: 4, f: 5, g: 7, a: 9, b: 11}[pc.toLowerCase()];
+  const offset = acc?.split("").reduce((o, char) => o + {"#": 1, b: -1}[char], 0) || 0;
+  return (Number(oct) + 1) * 12 + chroma + offset;
+};
+export const fromMidi = (n) => {
+  return Math.pow(2, (n - 69) / 12) * 440;
+};
+export const mod = (n, m) => n < 0 ? mod(n + m, m) : n % m;
+export const getPlayableNoteValue = (event) => {
+  let {value: note, context} = event;
+  if (typeof note === "number" && context.type !== "frequency") {
+    note = fromMidi(event.value);
+  } else if (typeof note === "string" && !isNote(note)) {
+    throw new Error("not a note: " + note);
+  }
+  return note;
+};