ReasonML Quick Start Guide

Js.t Object

BuckleScript allows us to access arbitrary JavaScript object fields using the ## syntax. We can use syntax on any Js.t type, which is a Reason type for arbitrary JavaScript objects. We'll learn more about this and other interoperability features in Chapter 4, BuckleScript, Belt, and Interoperability. 

Since ReactEvent.Touch.changedTouches(event) returns a plain old JavaScript object, we can access its fields using the following:

/* App.re */ReactEvent.Touch.changedTouches(event)##item(0)##clientX

Looking in the compiled output, we see that it is what we want:

/* App.bs.js */event.changedTouches.item(0).clientX

We'll use this to add the touch feature to our menu so that users can swipe the menu closed and see the menu move as they ...