Drag gesture, like the image above, is a very good interaction model for touch devices.
This article is about the implementation of drag gesture on mobile browsers.

I use react to simplify the code. However you can accomplish it without any framework.

The basic idea is to make a scrollable widget comprised by two component.
The first component is always visible while the second one(named drag-btn in this article) can only be seen after scrolling.

We use onscroll to monitor the scrolling.

When the user scrolls to certain position, we have to tell the user that the drag action is about to be triggered.This is fulfilled by adding another class to drag-btn component to change its color.

When the user stops scrolling, a touchend event is emitted which can be utilized to check if drag action should be executed.

In order to keep it concise, only the most pertinent code was demonstrated in this article.
For more details, check this repo.