ScalaJs 0.9: getting HTML input value without jQuery

Question

I'm using ScalaJS and I want to read the value of an HTML input element.

Here's the HTML code:

<input id="nodeValue" type="number" step="1" />

And this is the Scala code:

object TutorialApp extends JSApp {
    // ...
    def addNode() = {
        val nodeValue = document.getElementById("nodeValue").value.toInt
    }
}

It doesn't compile, as

[error] TutorialApp.scala:42: value value is not a member of org.scalajs.dom.raw.Element
[error]     val nodeValue = document.getElementById("nodeValue").value.toInt

In the documentation, I can't find the value attribute of org.scalajs.dom.raw.Element.

In the official basic tutorial it uses immediately to jQuery, but I'd avoid it since I'm working on a small proof of concept. I'm sure there's a way to use just the DOM API.

EDIT:

Going through the documentation I found the nodeValue method which returns a string. It says though that is null for "most node types". Mine is number and indeed fails at runtime, returning null. Another edit: it returns null also for a text input.

I feel a bit bewildered at this point.

thanks, Pietro

sjrd · Accepted Answer · 2016-07-21 14:41:55Z

7

I assume the element you're fetching (nodeValue) is an <input> element.

getElementById does not know what kind of element nodeValue is. It does not have access to the .html to figure that out, and hence it returns a very generic Element. But in fact, you know that it is an input element, i.e., an org.scalajs.dom.html.Input. You can tell that to the compiler with .asInstanceOf[html.Input]. A generic Element does not have a value property, only Inputs have.

import org.scalajs.dom.html

val nodeValue = document.getElementById("nodeValue").asInstanceOf[html.Input].value.toInt

answered Jul 21, 2016 at 14:41

sjrd

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1 Comment

gurghet Over a year ago

Would it be better to generate the html directly in scalajs? Like with scalatags?

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