initial

speci.js

@@ -0,0 +1,73 @@
+function doit() {
+
+    function make_x_first(x,y) {
+        return {x, y};
+    }
+
+    function make_y_first(x, y) {
+        return {y, x};
+    }
+
+    function make_random(x, y) {
+        if (Math.random() > 0.5) {
+            return make_y_first(x, y);
+        } else {
+            return make_x_first(x, y);
+        }
+    }
+
+    const million = 1000 * 1000;
+    const n = 10 * million;
+
+    function bulk(filler) {
+        let a = [];
+        for (let i = 0; i < n; i++) {
+            a.push(filler(i, i * i));
+        }
+        return a;
+    }
+
+    const x_first = bulk(make_x_first);
+    const y_first = bulk(make_y_first);
+    const mixed = bulk(make_random);
+
+    function time(func) {
+        const start = Date.now();
+        func();
+        const delta = Date.now() - start;
+        return delta;
+    }
+
+    function report(func) {
+        let delta = time(func);
+        console.log(`${delta} ms`);
+    }
+
+    function demo(dataSet) {
+        for (let i = 0; i < 3; i++) {
+            console.log(`run ${i+1}`);
+            report(() => {
+                let sumX = 0, sumY = 0;
+                for (let i = 0; i < dataSet.length; i++) {
+                    let item = dataSet[i];
+                    sumX += item.x;
+                    sumY += item.y;
+                }
+                return {x: sumX, y: sumY};
+            });
+            console.log(``);
+        }
+    }
+
+    console.log(`** x_first`);
+    demo(x_first);
+
+    console.log(`** y_first`);
+    demo(y_first);
+
+    console.log(`** mixed`);
+    demo(mixed);
+
+}
+
+doit();