js_util 0.2.0

  • README.md
  • Example
  • Installing
  • Versions
  • 40


Build Status

Utilities to access JavaScript from Dart.

  • toJS(o): Converts a Dart object to a JavaScript object.
  • newObject(): Creates a new JavaScript object.
  • defineProperty(o, String prop, PropertyDescription desc): A wrapper for Object.defineProperty
  • getValue(o, String prop): Returns o[prop].
  • setValue(o, String prop, value): Performs o[prop] = value.

These utilities are of great help if a JavaScript API takes a JavaScript object with keys that are not fixed because js package does not let you create a JavaScript object without declaring a Dart class with @JS() and @anonymous.

Getting Started

Include js_util.js in index.html to use js_util functions.

    <script async src="packages/js_util/dist/js_util.js"></script>
    <script async src="packages/browser/dart.js"></script>


A simple usage example:

final obj = newObject();
defineProperty(obj, 'foo', new PropertyDescription(enumerable: true, value: 1));
defineProperty(obj, 'bar', new PropertyDescription(enumerable: false, value: 2));
final obj = newObject();
setValue(obj, 'foo', 1);
setValue(obj, 'bar', 2);

print(getValue(obj, 'foo')); // 1
print(getValue(obj, 'bar')); // 2
final jsObj = toJS({
  'people': [
    {'firstName': 'Kwang Yul', 'lastName': 'Seo'},
    {'firstName': 'DoHyung', 'lastName': 'Kim'},
    {'firstName': 'Kyusun', 'lastName': 'Kim'}

final people = getValue(jsObj, 'people');
print(getValue(people[0], 'firstName')); // 'Kwang Yul'

Features and bugs

Please file feature requests and bugs at the issue tracker.



  • Add @JS annotations on library directives to support 1.16.0
  • Add the minified version of js_util.js


  • Initial version


import 'dart:html';

import 'package:js_util/js_util.dart';

void main() {
  final jsObj = toJS({
    'people': [
      {'firstName': 'Kwang Yul', 'lastName': 'Seo'},
      {'firstName': 'DoHyung', 'lastName': 'Kim'},
      {'firstName': 'Kyusun', 'lastName': 'Kim'}

  final people = getValue(jsObj, 'people');
  final firstPerson = people[0];
  final text =
      '${getValue(firstPerson, "firstName")} ${getValue(firstPerson, "lastName")}';
  document.querySelector('#container').innerHtml = text;

Use this package as a library

1. Depend on it

Add this to your package's pubspec.yaml file:

  js_util: ^0.2.0

2. Install it

You can install packages from the command line:

with pub:

$ pub get

Alternatively, your editor might support pub get. Check the docs for your editor to learn more.

3. Import it

Now in your Dart code, you can use:

import 'package:js_util/js_util.dart';
Version Uploaded Documentation Archive
0.2.0 May 2, 2016 Go to the documentation of js_util 0.2.0 Download js_util 0.2.0 archive
0.1.0 Mar 30, 2016 Go to the documentation of js_util 0.1.0 Download js_util 0.1.0 archive
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Learn more about scoring.

We analyzed this package on Jul 20, 2018, and provided a score, details, and suggestions below. Analysis was completed with status completed using:

  • Dart: 2.0.0-dev.69.0
  • pana: 0.11.7


Detected platforms: web, other

Primary library: package:js_util/js_util.dart with components: js.

Issues and suggestions

Support Dart 2 in pubspec.yaml.

The SDK constraint in pubspec.yaml doesn't allow the Dart 2.0.0 release. For information about upgrading it to be Dart 2 compatible, please see https://www.dartlang.org/dart-2#migration.

Package is too old.

The package was released more than two years ago.

The description is too short.

Add more detail about the package, what it does and what is its target use case. Try to write at least 60 characters.

Package is pre-v1 release.

While there is nothing inherently wrong with versions of 0.*.*, it usually means that the author is still experimenting with the general direction of the API.


Package Constraint Resolved Available
Direct dependencies
Dart SDK >=1.8.0 <2.0.0
js >=0.6.0 <0.7.0 0.6.1+1
quiver_iterables >=1.0.0 <2.0.0 1.0.1
Transitive dependencies
meta 1.1.6
Dev dependencies
browser >=0.10.0 <0.11.0
test >=0.12.0 <0.13.0