fix(core): update

ts/helpers/stats.ts

@@ -0,0 +1,43 @@
+export function average(values) {
+  let total = 0;
+
+  for (let i = 0; i < values.length; i += 1) {
+    total += values[i];
+  }
+
+  return total / values.length;
+}
+
+export function median(values) {
+  const half = Math.floor(values.length / 2);
+
+  values.sort((a, b) => a - b);
+
+  if (values.length % 2) return values[half];
+
+  return (values[half - 1] + values[half]) / 2;
+}
+
+export function quartile(values, percentile) {
+  values.sort((a, b) => a - b);
+  const pos = (values.length - 1) * percentile;
+  const base = Math.floor(pos);
+  const rest = pos - base;
+
+  if (values[base + 1] !== undefined) {
+    return values[base] + rest * (values[base + 1] - values[base]);
+  }
+
+  return values[base];
+}
+
+export function jitter(values) {
+  // Average distance between consecutive latency measurements...
+  let jitters = [];
+
+  for (let i = 0; i < values.length - 1; i += 1) {
+    jitters.push(Math.abs(values[i] - values[i + 1]));
+  }
+
+  return average(jitters);
+}