Issue using javascript library from within scala.js anonymous class

Question

I'm trying to use this javascript library from my scala.js app (simplified runnable example).

I can successfully use some parts of the api, but for other parts I'm having trouble determining the correct type signatures for my Scala facade.

For example, if a javascript function returns { text: 'June 5th 1998', ... } I can define scala.js classes to represent the function and the following succeeds:

class Value extends js.Object {
  def date(): js.Dictionary[Int] = js.native
}

object nlp extends js.Object {
  def sentences(text: String): js.Array[Sentence] = js.native
  def value(text: String): Value = js.native
}

nlp.value("I married April on June 6th 1998.").date()

However I have less luck if the javascript returns an array of the same (e.g.[{ text: ...}, { text: ...}]), or even if it returns a simple String (e.g."June 5th and June 6th" as the following compiles but fails at runtime with Uncaught TypeError: arg1$4.text is not a function:

class Sentence extends js.Object {
  def text(): String = js.native
  def values(): js.Array[Value] = js.native
}
val sentences = nlp.sentences(splittableText)
sentences.map( sentence => sentence.values() )
// Or `sentences.map( sentence => sentence.text() )`

How can I use this javascript api from scala.js?

Thanks very much for taking a look.

sjrd · Accepted Answer · 2015-11-15 20:23:54Z

1

text is a property (or field) in the objects returned by sentences. It's not a method. So you have to declare it as a def without ():

def text: String = js.native

answered Nov 15, 2015 at 20:23

sjrd

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5 Comments

Julian Peeters Over a year ago

After making the change, I seem to get:

Uncaught scala.scalajs.runtime.UndefinedBehaviorError: An undefined behavior was detected: undefined is not an instance of java.lang.String

sjrd Over a year ago

Then that means it doesn't have a text field/method at all. Check their API.

Julian Peeters Over a year ago

Thanks for the help with this. The text field should be there, it's the 2nd example in the docs, and it is there in the Sentence definition. I wasn't sure how to represent the javascript Sentence function with a Scala FunctionXX, and so I represented it with a Class -- could that be playing a role here?

sjrd Over a year ago

Your code above does not correspond to the example you link to. That example shows to access it as nlp.pos(...).sentences[0], which means that pos (not sentences) returns a js.Array[Sentence].

Julian Peeters Over a year ago

Apparently one can get sentences from nlp as well, but rewriting to use pos gave a different error:

Uncaught scala.scalajs.runtime.UndefinedBehaviorError: An undefined behavior was detected: function (){return b.tokens.map(function(a){return a.text}).join(" ")} is not an instance of java.lang.String

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