ゼロ幅スペースで頑張る

Author: Goryudyuma

src/post/renderer.test.ts

@@ -485,15 +485,18 @@ describe("Renderer", () => {
     expect(match).not.toBeNull();
     const labels: string[] = JSON.parse(match![1]);
 
+    const hasVisibleCharacters = (label: string): boolean =>
+      /[0-9:]/.test(label);
+
     expect(labels.length).toBe(times.length);
     expect(labels[0]).toBe(firstLabel);
     expect(labels[labels.length - 1]).toBe(lastLabel);
-    const visibleLabelCount: number = labels.filter(
-      (label: string): boolean => label.trim().length > 0,
-    ).length;
+    const visibleLabelCount: number = labels.filter(hasVisibleCharacters).length;
     expect(visibleLabelCount).toBeLessThanOrEqual(MAX_VISIBLE_TIME_LABELS);
-    expect(
-      labels.some((label: string): boolean => label.trim().length === 0),
-    ).toBe(true);
+    const hiddenLabels: string[] = labels.filter(
+      (label: string): boolean => !hasVisibleCharacters(label),
+    );
+    expect(hiddenLabels.length).toBe(times.length - visibleLabelCount);
+    expect(new Set(hiddenLabels).size).toBe(hiddenLabels.length);
   });
 });

src/post/renderer.ts

@@ -7,7 +7,9 @@ import type {
 } from "./lib";
 
 export const MAX_VISIBLE_TIME_LABELS: number = 12;
-const EMPTY_TIME_LABEL_PLACEHOLDER: string = " ";
+const ZERO_WIDTH_ZERO: string = "\u200b";
+const ZERO_WIDTH_ONE: string = "\u200c";
+const ZERO_WIDTH_SENTINEL: string = "\u200d";
 
 const formatTimeLabels = (times: Date[]): string[] => {
   if (times.length === 0) {
@@ -25,16 +27,27 @@ const formatTimeLabels = (times: Date[]): string[] => {
   const usableSlots: number = Math.max(MAX_VISIBLE_TIME_LABELS - 2, 1);
   const spacing: number = Math.ceil((formattedTimes.length - 2) / usableSlots);
 
+  const encodeHiddenLabel = (index: number): string => {
+    const binary: string = index.toString(2);
+    return (
+      ZERO_WIDTH_SENTINEL +
+      binary
+        .split("")
+        .map((digit: string): string =>
+          digit === "0" ? ZERO_WIDTH_ZERO : ZERO_WIDTH_ONE,
+        )
+        .join("")
+    );
+  };
+
   return formattedTimes.map(
     (label: string, index: number, array: string[]): string => {
       if (index === 0 || index === array.length - 1) {
         return label;
       }
 
       const normalizedIndex: number = index - 1;
-      return normalizedIndex % spacing === 0
-        ? label
-        : EMPTY_TIME_LABEL_PLACEHOLDER;
+      return normalizedIndex % spacing === 0 ? label : encodeHiddenLabel(index);
     },
   );
 };