Wednesday, February 14, 2018

Understanding JsInterop


I am trying to get a DOMRect from an Element. I can do this with JSNI, but have been unable to make a JsInterop version. Here's what I have:

public final class DOMRect extends JavaScriptObject
 // returns DOMRect or null
 public static native DOMRect getBoundingClientRect(Element element)
 return element.getBoundingClientRect && element.getBoundingClientRect();

 protected DOMRect()

 public final native double getX()
 return this.x;

 // etc.

I can make a JsType for DOMRect, no problem. The issue I'm having is with getBoundingClientRect(). This function may not exist which is why there is a null check. If I make an interface for getBoundingClientRect, I'm not allowed to cast Element to implement it. I can't extend Element, either. With JSNI, I am allowed to compile Javascript into Javascript, but I can't with JsInterop. It seems like a lot of trouble for 1 line of Javascript.

How can I do this? Thanks in advance...

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