Browsers have supported various mouse-based events like clicks, down to the detection of when the mouse button is down and when it's released. You can know the coordinates of the mouse cursor, all in JavaScript. Mobile interfaces have brought some new gestures beyond what desktops provided. One big set of such UI events is from the smartphone's screen allowing touch and even multi-touch. Multitouch allows more types of UI events.
Many mobile apps support swiping, not just as a way to move a visible object around thescreen but applied for the whole screen. Tinder uses left swipe and...