Add optional seconds picker

src/models/second.ts

@@ -0,0 +1,26 @@
+import { DEFAULT_SECOND_STEP } from '../const';
+import { TimeUnit } from './time-unit';
+import { Direction } from '../types';
+
+/**
+ * * Represents the second value of a datetime.
+ */
+export class Second extends TimeUnit {
+  private static readonly VALUE_LIMIT = 60;
+
+  minValue = 0;
+  maxValue = Second.VALUE_LIMIT - 1;
+
+  constructor(value: number, step = DEFAULT_SECOND_STEP) {
+    super(value, step, Second.VALUE_LIMIT);
+  }
+
+  /**
+   * Returns true if the seconds will overflow to a different hour when changed in {@param direction}.
+   * @param direction
+   */
+  willOverflow(direction: Direction): boolean {
+    const newValue = direction === Direction.UP ? this.value + this._step : this.value - this._step;
+    return newValue >= this._limit || newValue < 0;
+  }
+}