Create js Objects from Dart

Question

I have js code that needs to be translatable to Dart:

(function() {
    var s, e;
    s = document.createElement("script");
    s.src = “//someurl.com/somefile.js";
    s.async = true;
    e = document.getElementsByTagName("head")[0];
    e.insertBefore(s, e.firstChild);
    this.OBJECT = this.OBJECT || {};
    this.OBJECT.array = this.OBJECT.somearray || [];
})();

OBJECT.somearray.push({
    val1 : “foo",
    val2 : “bar"
});

Basic part to embed script into head I did like this:

ScriptElement scr = new ScriptElement()
  ..src = "//someurl.com/somefile.js";
  ..async = true;
querySelector('head').append(scr);

But I don't know how to correctly check if OBJECT and OBJECT.somearray exists in somefile.js and push an object item in it.

Do you think that I didn't tried to look for it in google on dart documentation before post it here? I will be much helpful if you could help to me with some example code. — Vladimirs Matusevics
– Vladimirs Matusevics, Commented Dec 14, 2013 at 18:20
But... the documentation has example code :-/ Here as well. To create an object, call new JsObject(context['Object']), to create an array, new JsObject(context['Array']). There is also JsArray which might be helpful. I mean, I don't know where exactly you are stuck. If you post what you have tried and which error you get, we might be able to help you better. — Felix Kling
– Felix Kling, Commented Dec 14, 2013 at 18:23

Alexandre Ardhuin · Accepted Answer · 2013-12-14 20:30:03Z

1

With dart:js you can check the presence of a global variable with :

bool exist = context.hasProperty('OBJECT');
if (exist) {
  final o = context['OBJECT'];
  if (!o.hasProperty('somearray')) {
    o['somearray'] = new JsArray();
  }
}

answered Dec 14, 2013 at 20:30

Alexandre Ardhuin

76.9k17 gold badges162 silver badges136 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

ins0m · Accepted Answer · 2013-12-14 18:45:49Z

0

You are mixing some things up, especially the scope of the function of your JS. I don't want to make assumptions about your js, but it looks as if you do not properly initialize your OBJECT. You want to add something like this to your javascript

function myObject(){
  this.array = []
}

In dart you can, as Felix pointed out in the comments then create this function. There are different options. One is to access JS functions via dart:js (see felix comment), another is to use the js-interop library. I am not particularly sure what the differences are but i find the js-interop library to have a much cleaner API (https://github.com/dart-lang/js-interop)

import 'package:js/js.dart' as js;
var yourObject = js.Proxy(js.context.myObject);
yourObject.array.push("...");

js.interop makes javascript calls available on an object, rather than using callMethod etc. but I guess it relies on dart2js rather than dart only.

edited Dec 14, 2013 at 18:45

answered Dec 14, 2013 at 18:36

ins0m

84810 silver badges20 bronze badges

1 Comment

Alexandre Ardhuin Over a year ago

The cleaner API comes with a cost in size and speed (because package:js uses dart:mirrors and noSuchMethod).

Collectives™ on Stack Overflow

Create js Objects from Dart

2 Answers 2

Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related