Function RequestInterval

src/js/constructors/RequestInterval/RequestInterval.ts:28–149

(
  interval: number,
  onInterval: () => void,
  onUpdate?: ( rate: number ) => void,
  limit?: number
)

 * @param limit      - Optional. Limits the number of interval.
 */
export function RequestInterval(
  interval: number,
  onInterval: () => void,
  onUpdate?: ( rate: number ) => void,
  limit?: number
): RequestIntervalInterface {
  const { now } = Date;

  /**
   * The time when the interval starts.
   */
  let startTime: number;

  /**
   * The current progress rate.
   */
  let rate = 0;

  /**
   * The animation frame ID.
   */
  let id: number;

  /**
   * Indicates whether the interval is currently paused or not.
   */
  let paused = true;

  /**
   * The loop count. This only works when the `limit` argument is provided.
   */
  let count = 0;

  /**
   * The update function called on every animation frame.
   */
  function update(): void {
    if ( ! paused ) {
      rate = interval ? min( ( now() - startTime ) / interval, 1 ) : 1;
      onUpdate && onUpdate( rate );

      if ( rate >= 1 ) {
        onInterval();
        startTime = now();

        if ( limit && ++count >= limit ) {
          return pause();
        }
      }

      id = raf( update );
    }
  }

  /**
   * Starts the interval.
   *
   * @param resume - Optional. Whether to resume the paused progress or not.