🚀 UI components for dojo2.
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Latest commit 9aa1829 Jan 16, 2017 @agubler agubler committed on GitHub make properties attribute readonly (#239)



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A core widget library for Dojo.

WARNING This is alpha software. It is not yet production ready, so you should use at your own risk.

For more background on @dojo/widgets, there is a document describing the widgeting system.


To use @dojo/widgets in a project install the package along with the required peer dependencies.

npm install @dojo/widgets

# peer dependencies
npm install @dojo/has
npm install @dojo/shim
npm install @dojo/core
npm install @dojo/compose

To use @dojo/widgets, import the module in the project. For more details see features below.

import createButton from '@dojo/widgets/components/button/createButton';

or use the dojo cli to create a complete Dojo skeleton application.


@dojo/widgets are based on a virtual DOM implementation named Maquette as well as some foundational classes provided in @dojo/compose.

The smallest @dojo/widgets example looks like this:

const projector = createProjector();
projector.children = [ v('h1', [ 'Hello, Dojo!' ]) ];

It renders a h1 element saying "Hello, Dojo!" on the page. See the following sections for more details.


These are some of the important principles to keep in mind when developing widgets:

  1. the widget render function should never be overridden
  2. with the exception of the top level projector you should never have to deal with widget instances.
  3. hyperscript should always be written using the @dojo/widgets v helper function.
  4. state should never be set outside of the widget instance.

Base Widget

The class createWidgetBase provides all base @dojo/widgets functionality including caching and widget lifecycle management. It can be used directly or extended to create custom widgets.

Widget API

A subset of the Widget API are intended to be overridden in scenarios where the default implemented behviour does not suffice.

Function Description Default Behaviour
getNode Returns the top level node of a widget Returns a DNode with the widgets tagName, the result of this.getNodeAttributes and this.children
getChildrenNodes Returns the child node structure of a widget Returns the widgets children DNode array
nodeAttributes An array of functions that return VNodeProperties to be applied to the top level node Returns attributes for data-widget-id, classes and styles using the widget's specified state (id, classes, styles) at the time of render
diffProperties Diffs the current properties against the previous properties and returns the updated/new keys in an array Performs a shallow comparison using === of previous and current properties and returns an array of the keys.
applyChangedProperties Gets called to apply updated/new properties If there are updated properties they are directly set onto the widgets state using setState.

To customise the widget an optional options argument can be provided with the following interface.

Type: WidgetOptions<WidgetState, WidgetProperties> - All properties are optional.

Property Type Description
id string identifier for the widget
stateFrom StoreObservablePatchable Observable that provides state for the widget
listeners EventedListenersMap Map of listeners for to attach to the widget
tagName string Override the widgets tagname
properties WidgetProperties Props to be passed to the widget. These can be used to determine state internally
nodeAttributes Function[] An array of functions that return VNodeProperties to be applied to the VNode

A widgets' state should never be directly set outside of the instance. In order to manipulate widget state, properties should be updated such as widget.properties = { 'foo': 'bar' } and then during the next render the new or updated properties are passed to instance#applyChangedProperties.

As a convenience, all event handlers are automatically bound to the widget instance, so state and other items on the instance can be easily accessed.

Simple Widgets

To create a basic widget createWidgetBase can be used directly by importing the class.

import createWidgetBase from '@dojo/widgets/createWidgetBase';

const myBasicWidget = createWidgetBase();

The widget creates the following DOM element:


The following example demonstrates how id, classes and styles are applied to the generated DOM.

import createWidgetBase from '@dojo/widgets/createWidgetBase';

const myBasicWidget = createWidgetBase({
    properties: {
        id: 'my-widget',
        classes: [ 'class-a', 'class-b' ],
        styles: [ 'width:20px' ]

The widget creates the following DOM element:

<div data-widget-id="my-widget" class="class-a class-b" styles="width:20px"></div>

Alternatively state can be derived directly from an observable store passed via stateFrom. The following code will create the same DOM element as the above example.

const widgetStore = createObservableStore({
    data: [
            id: 'my-widget',
            classes: [ 'class-a', 'class-b' ],
            styles: [ 'width:20px' ]

const myBasicWidget = createWidgetBase({
    id: 'my-widget',
    stateFrom: widgetStore


d is the module that provides the functions and helper utilities that can be used to express widget structures within Dojo 2. This structure constructed of DNodes (DNode is the intersection type of HNode and WNode).

When creating custom widgets, you use the v and w functions from the d module.

It is imported by:

import { v, w } from '@dojo/widgets/d';

The argument and return types are available from @dojo/widgets/interfaces as follows:

import { DNode, HNode, WNode } from '@dojo/widgets/interfaces';

v is an abstraction of Hyperscript that allows dojo 2 to manage caching and lazy creation.

Creates an element with the specified tag

v(tag: string): HNode[];

where tag is in the form: element.className(s)#id, e.g.

h2 h2.foo h2.foo.bar h2.foo.bar#baz h2#baz

classNames must be period (.) delimited if more than 1 class is specified. Please note, both the classes and id portions of the tag are optional.

The results of the invocations above are:

h2                  (<h2></h2>)
h2.foo              (<h2 class="foo"></h2>)
h2.foo.bar          (<h2 class="foo bar"></h2>)
h2.foo.bar#baz      (<h2 class="foo bar" id="baz"></h2>)
h2#baz              (<h2 id="baz"></h2>)

Creates an element with the tag with the children specified by the array of DNode, VNode, string or null items.

v(tag: string, children: (DNode | null)[]): HNode[];

Creates an element with the tagName with VNodeProperties options and optional children specified by the array of DNode, VNode, string or null items.

v(tag: string, properties: VNodeProperties, children?: (DNode | null)[]): HNode[];

The d module exports a global registry to be used to define a factory label against a WidgetFactory, Promise<WidgetFactory> or () => Promise<WidgetFactory.

This enables consumers to specify a string label when authoring widgets using the w function (see below) and allows the factory to resolve asyncronously (for example if the module had not been loaded).

import { registry } from '@dojo/widgets/d';
import createMyWidget from './createMyWidget';

// registers the widget factory that will be available immediately
registry.define('my-widget-1', createMyWidget);

// registers a promise that is resolving to a widget factory and will be
// available as soon as the promise resolves.
registry.define('my-widget-2', Promise.resolve(createMyWidget));

// registers a function that will be lazily executed the first time the factory
// label is used within a widget render pipeline. The widget will be available
// as soon as the promise is resolved after the initial get.
registry.define('my-widget-3', () => Promise.resolve(createMyWidget));

It is recommmended to use the factory registry when defining widgets using w in order to support lazy factory resolution when required. Example of registering a function that returns a Promise that resolves to a Factory.

import load from '@dojo/core/load';

registry.define('my-widget', () => {
    return load(require, './createMyWidget')
        .then(([ createMyWidget ]) => createMyWidget.default);

w is an abstraction layer for @dojo/widgets that enables dojo 2's lazy instantiation, instance management and caching.

Creates a @dojo/widget using the factory and options.

w(factory: string | ComposeFactory<W, O>, options: O): WNode[];

Creates a @dojo/widget using the factory, options and children

w(factory: string | ComposeFactory<W, O>, options: O, children: (DNode | null)[]): WNode[];

Example w constucts:

w(createFactory, options, children);
w('my-factory', options, children);

Authoring Widgets

To create custom reusable widgets you can extend createWidgetBase.

A simple widget with no children such as a label widget can be created like this:

import { ComposeFactory } from '@dojo/compose/compose';
import { VNodeProperties } from '@dojo/interfaces/vdom';
import { Widget, WidgetOptions, WidgetState } from '@dojo/widgets/interfaces';
import createWidgetBase from '@dojo/widgets/createWidgetBase';

interface LabelState extends WidgetState {
    label?: string;

interface LabelOptions extends WidgetOptions<LabelState> { }

type Label = Widget<LabelState>;

interface LabelFactory extends ComposeFactory<Label, LabelOptions> { }

const createLabelWidget: LabelFactory = createWidgetBase.mixin({
    mixin: {
        tagName: 'label',
        nodeAttributes: [
            function(this: Label): VNodeProperties {
                return { innerHTML: this.state.label };

export default createLabelWidget;

With its usages as follows:

import createLabelWidget from './widgets/createLabelWidget';

const label = createLabelWidget({ state: { label: 'I am a label' }});

To create structured widgets override the getChildrenNodes function.

import { ComposeFactory } from '@dojo/compose/compose';
import { DNode, Widget, WidgetOptions, WidgetState } from '@dojo/widgets/interfaces';
import createWidgetBase from '@dojo/widgets/createWidgetBase';
import { v } from '@dojo/widgets/d';

interface ListItem {
    name: string;

interface ListState extends WidgetState {
    items?: ListItem[];

interface ListOptions extends WidgetOptions<ListState> { };

type List = Widget<ListState>;

interface ListFactory extends ComposeFactory<List, ListOptions> { };

function isEven(value: number) {
    return value % 2 === 0;

function listItem(item: ListItem, itemNumber: number): DNode {
    const classes = isEven(itemNumber) ? {} : { 'odd-row': true };
    return v('li', { innerHTML: item.name, classes });

const createListWidget: ListFactory = createWidgetBase.mixin({
    mixin: {
        getChildrenNodes: function (this: List): DNode[] {
            const { items = [] } = this.state;
            const listItems = items.map(listItem);

            return [ v('ul', {}, listItems) ];

export default createListWidget;

Event Handlers

The recommended pattern for event handlers is to declare them on the widget class, referencing the function using this most commonly within getChildrenNodes or a nodeAttributes function.

Event handlers can be internal logic encapsulated within a widget as shown in the first example or they can delegate to a function that is passed via properties as shown in the second example.

internally defined handler

const createMyWidget: MyWidgetFactory = createWidgetBase.mixin({
    mixin: {
        onClick: function (this: MyWidget): void {
        getChildrenNodes(this: MyWidget): DNode[] {
            const { state: { selected } } = this;

            return [
                v('input', { type: 'checkbox', onclick: this.onClick }),
                v('input', { type: 'text', disabled: this.state.selected })

Handler passed via properties

const createMyWidget: MyWidgetFactory = createWidgetBase.mixin({
    mixin: {
        onClick: function (this: MyWidget): void {


To render widgets they must be appended to a projector. It is possible to create many projectors and attach them to Elements in the DOM, however projectors must not be nested.

The projector works in the same way as any widget overridding getChildrenNodes when createProjector class is used as the base for a custom widget (usually the root of the application).

In addition when working with a projector you can also set the children directly.

The standard WidgetOptions are available and also createProjector adds two additional optional properties root and cssTransitions.

  • root - The Element that the projector attaches to. The default value is document.body
  • cssTransitions - Set to true to support css transitions and animations. The default value is false.

Note: If cssTransitions is set to true then the projector expects Maquette's css-transitions.js to be loaded.

In order to attach the createProjector to the page call either .append, .merge or .replace depending on the type of attachment required and it returns a promise.

Instantiating createProjector directly:

import { DNode } from '@dojo/widgets/interfaces';
import { w } from '@dojo/widgets/d';
import createProjector, { Projector } from '@dojo/widgets/createProjector';
import createButton from '@dojo/widgets/components/button/createButton';
import createTextInput from '@dojo/widgets/components/textinput/createTextInput';

const projector = createProjector();

projector.children = [
    w(createTextInput, { id: 'textinput' }),
    w(createButton, { id: 'button', properties: { label: 'Button' } })

projector.append().then(() => {
    console.log('projector is attached');

Using the createProjector as a base for a root widget:

import { DNode } from '@dojo/widgets/interfaces';
import { w } from '@dojo/widgets/d';
import createProjector, { Projector } from '@dojo/widgets/createProjector';
import createButton from '@dojo/widgets/components/button/createButton';
import createTextInput from '@dojo/widgets/components/textinput/createTextInput';

const createApp = createProjector.mixin({
    mixin: {
        getChildrenNodes: function(this: Projector): DNode[] {
            return [
                w(createTextInput, { id: 'textinput' }),
                w(createButton, { id: 'button', properties: { label: 'Button' } })
        classes: [ 'main-app' ],
        tagName: 'main'

export default createApp;

Using the custom widget assuming a class called createApp.ts relative to its usages:

import createApp from './createApp';

const app = createApp();

app.append().then(() => {
    console.log('projector is attached');


Widgets can be internationalized by mixing in @dojo/widgets/mixins/createI18nMixin. Message bundles are localized by passing them to localizeBundle. If the bundle supports the widget's current locale, but those locale-specific messages have not yet been loaded, then the default messages are returned and the widget will be invalidated once the locale-specific messages have been loaded. Each widget can have its own locale by setting its state.locale; if no locale is set, then the default locale as set by @dojo/i18n is assumed.

const createI18nWidget = createWidgetBase
        mixin: {
            nodeAttributes: [
                function (attributes: VNodeProperties): VNodeProperties {
                    // Load the `greetings` messages for the current locale.
                    const messages = this.localizeBundle(greetings);
                    return { title: messages.hello };

            getChildrenNodes: function () {
                // Load the "greetings" messages for the current locale. If the locale-specific
                // messages have not been loaded yet, then the default messages are returned,
                // and the widget will be invalidated once the locale-specific messages have
                // loaded.
                const messages = this.localizeBundle(greetingsBundle);

                return [
                    d(createLabel, {
                        state: {
                            // Passing a message string to a child widget.
                            label: messages.purchaseItems
                    d(createButton, {
                        state: {
                            // Passing a formatted message string to a child widget.
                            label: messages.format('itemCount', { count: 2 })

const widget = createI18nWidget({
    state: {
        // Set the locale for the widget and all of its children. Any child can still
        // set its own locale.
        locale: 'fr'

Dojo Widget Components

A selection of core reusable widgets are provided for convenience that are fully accessible and open to internationalization.

// TODO - list core components here.

How Do I Contribute?

We appreciate your interest! Please see the Dojo Meta Repository for the Contributing Guidelines and Style Guide.


To start working with this package, clone the repository and run npm install.

In order to build the project run grunt dev or grunt dist.


Test cases MUST be written using Intern using the Object test interface and Assert assertion interface.

90% branch coverage MUST be provided for all code submitted to this repository, as reported by istanbul’s combined coverage results for all supported platforms.

To test locally in node run:

grunt test

To test against browsers with a local selenium server run:

grunt test:local

To test against BrowserStack or Sauce Labs run:

grunt test:browserstack


grunt test:saucelabs

Licensing Information

© 2016 JS Foundation. New BSD license.