Docs: Update benchmark for stealth/union-alpha EFF:high

tests/9_stream_visualizer/outputs/stealth_union-alpha EFF_high.js

@@ -0,0 +1,63 @@
+async function createStreamVisualizer(asyncIterable, options = {}) {
+  const { maxPoints, alpha, width, height, yDomain } = options;
+
+  if (typeof asyncIterable?.[Symbol.asyncIterator] !== "function")
+    throw new TypeError("Expected an async iterable.");
+
+  if (!Number.isSafeInteger(maxPoints) || maxPoints < 1)
+    throw new RangeError("maxPoints must be a positive safe integer.");
+
+  if (!Number.isFinite(alpha) || alpha < 0 || alpha > 1)
+    throw new RangeError("alpha must be between 0 and 1.");
+
+  if (![width, height].every(n => Number.isFinite(n) && n >= 0))
+    throw new RangeError("width and height must be finite and nonnegative.");
+
+  if (
+    !Array.isArray(yDomain) ||
+    yDomain.length !== 2 ||
+    !yDomain.every(Number.isFinite) ||
+    yDomain[0] >= yDomain[1]
+  )
+    throw new RangeError("yDomain must contain two increasing finite numbers.");
+
+  const domain = [...yDomain];
+  const d3 = await import("https://cdn.jsdelivr.net/npm/d3@7.9.0/+esm");
+  const buffer = [];
+  let cursor = 0, ema;
+
+  for await (const point of asyncIterable) {
+    const { timestamp, value } = point ?? {};
+    const time = timestamp instanceof Date ? timestamp.getTime() : timestamp;
+
+    if (!Number.isFinite(time) || !Number.isFinite(value))
+      throw new TypeError("Each point needs a valid timestamp and finite value.");
+
+    ema = ema === undefined ? value : alpha * value + (1 - alpha) * ema;
+    buffer[cursor] = { timestamp: time, value, ema };
+    cursor = (cursor + 1) % maxPoints;
+  }
+
+  const data = buffer.length === maxPoints
+    ? buffer.slice(cursor).concat(buffer.slice(0, cursor))
+    : buffer;
+
+  if (!data.length) return { data, path: "" };
+
+  const x = d3.scaleLinear()
+    .domain([data[0].timestamp, data[data.length - 1].timestamp])
+    .range([0, width]);
+
+  const y = d3.scaleLinear()
+    .domain(domain)
+    .range([height, 0]);
+
+  const path = d3.line()
+    .x(d => x(d.timestamp))
+    .y(d => y(d.ema))(data) ?? "";
+
+  return { data, path };
+}
+export default createStreamVisualizer;
+// Generation time: 101.222s
+// Result: PASS