fix(hooks): refactor useCountDown hook for improved countdown logic and clarity.

packages/hooks/src/use-count-down.ts

@@ -2,40 +2,59 @@ import { computed, onScopeDispose, ref } from 'vue';
 import { useRafFn } from '@vueuse/core';
 
 /**
- * count down
+ * A hook for implementing a countdown timer. It uses `requestAnimationFrame` for smooth and accurate timing,
+ * independent of the screen refresh rate.
  *
- * @param seconds - count down seconds
+ * @param initialSeconds - The total number of seconds for the countdown.
  */
-export default function useCountDown(seconds: number) {
-  const FPS_PER_SECOND = 60;
+export default function useCountDown(initialSeconds: number) {
+  const remainingSeconds = ref(0);
 
-  const fps = ref(0);
+  const count = computed(() => Math.ceil(remainingSeconds.value));
 
-  const count = computed(() => Math.ceil(fps.value / FPS_PER_SECOND));
-
-  const isCounting = computed(() => fps.value > 0);
+  const isCounting = computed(() => remainingSeconds.value > 0);
 
   const { pause, resume } = useRafFn(
-    () => {
-      if (fps.value > 0) {
-        fps.value -= 1;
-      } else {
+    ({ delta }) => {
+      // delta: milliseconds elapsed since the last frame.
+
+      // If countdown already reached zero or below, ensure it's 0 and stop.
+      if (remainingSeconds.value <= 0) {
+        remainingSeconds.value = 0;
+        pause();
+        return;
+      }
+
+      // Calculate seconds passed since the last frame.
+      const secondsPassed = delta / 1000;
+      remainingSeconds.value -= secondsPassed;
+
+      // If countdown has finished after decrementing.
+      if (remainingSeconds.value <= 0) {
+        remainingSeconds.value = 0;
         pause();
       }
     },
-    { immediate: false }
+    { immediate: false } // The timer does not start automatically.
   );
 
-  function start(updateSeconds: number = seconds) {
-    fps.value = FPS_PER_SECOND * updateSeconds;
+  /**
+   * Starts the countdown.
+   *
+   * @param [updatedSeconds=initialSeconds] - Optionally, start with a new duration. Default is `initialSeconds`
+   */
+  function start(updatedSeconds: number = initialSeconds) {
+    remainingSeconds.value = updatedSeconds;
     resume();
   }
 
+  /** Stops the countdown and resets the remaining time to 0. */
   function stop() {
-    fps.value = 0;
+    remainingSeconds.value = 0;
     pause();
   }
 
+  // Ensure the rAF loop is cleaned up when the component is unmounted.
   onScopeDispose(() => {
     pause();
   });