[SOLVED] How to deeply compare two js like objects in scala.js?

How to deeply compare two js like objects in scala.js?

Since js.Dynamic.literal() != js.Dynamic.literal(), what is the suggested way to test equality for two literals?

I don't want to characterize those literals with traits. I want to know if they are deeply equal.

What I'm doing right now is the following

val js1 = literal()
val js2 = literal()
val json1 = JSON.stringify(js1)
val json2 = JSON.stringify(js2)
assert(json1 == json2) // true

Note: even in javascript {} === {} evaluates to false, so I shouldn't have been surprised in the first place.

Solution

You could define your own structural equality for JS object-like structures:

def jsStructuralEqual(a: Any, b: Any): Boolean = {
  (a, b) match {
    case (a: js.Array[_], b: js.Array[_]) =>
      a.length == b.length &&
      a.zip(b).forall((jsStructuralEqual _).tupled)

    case _ if a.constructor == js.constructorOf[js.Object] &&
        b.constructor == js.constructorOf[js.Object] =>
      val aDict = a.asInstanceOf[js.Dictionary[Any]]
      val bDict = b.asInstanceOf[js.Dictionary[Any]]
      (aDict.keySet == bDict.keySet) &&
      aDict.keySet.forall(key => jsStructuralEqual(aDict(key), bDict(key))

    case _ =>
      a == b
  }
}

(not tested)