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@implab/djx
SYNOPSIS
import { djbase, djclass, bind, prototype, AbstractConstructor } from "@implab/djx/declare"; import { DjxWidgetBase } from "@implab/djx/tsx/DjxWidgetBase"; import { createElement } from "@implab/djx/tsx"; interface MyWidgetAttrs { title: string; counter: number; } interface MyWidgetEvents { "count-inc": Event; "count-dec": Event; } @djclass export class MyWidget extends djbase( DjxWidgetBase as AbstractConstructor<DjxWidgetBase<MyWidgetAttrs, MyWidgetEvents>> ) { @bind({ node: "titleNode", type: "innerHTML" }) title = ""; @prototype() counter = 0; render() { const Frame = (props: any) => <div>{props.children}</div>; return <div className="myWidget" tabIndex={3} style={ alignContent: "center", border: "1px solid" } > <h1 data-dojo-attach-point="titleNode"></h1> <Frame> <span class="up-button" onclick={e => this._onIncClick(e)}>[+]</span> <span class="down-button" onclick={() => this._onDecClick()}>[-]</span> </Frame> </div>; } _onIncClick(e: MouseEvent) { this.emit("count-inc", { bubbles: false }); } _onDecClick() { this.emit("count-dec", { bubbles: false }); } }
DESCRIPTION
This package provides you with the tools to glue your good-fellow dojo with modern techniques of building the webapp. The core concept is to built around widgets and using .tsx to write it. Here are some features:
djbase()
,@djaclass
- traits to declare your classes withdojo/_base/declare
@implab/djx/tsx
- traits to build the rendering of your widgets with tsxDjxWidgetBase
- abstract class which supports tsx markup anddata-dojo-attach-*
attributes.@bind(...)
- annotations provide an easy way of using standard dojo widget attribute bindings.
djbase, @djclass
These two traits provide convenient way of using dojo/_base/declare
in Typescript
for declaring your classes.
djbase(...constructors)
- this method accepts a list of constructors in its
parameters and returns the fake base type which then can be used to derive
your own class. This allows you to provide the Typescript with the correct
information about the base type and even use super
!. The only caveat of
this approach is that you MUST decorate your class with @djclass
annotation.
Consider the following example:
import { djbase, djclass } from "@implab/djx/declare"; import { FooMixin } from "./FooMixin"; import { BarMixin } from "./BarMixin"; import { BoxMixin } from "./BoxMixin"; @djclass export class Baz extends djbase(FooMixin, BarMixin, BoxMixin) { writeHello(out: string[]) { out.push("-> Baz"); super.writeHello(out); out.push("<- Baz"); } }
All mixins are declared like the one below:
import { djclass, djbase } from "@implab/djx/declare"; interface Super { writeHello(out: string[]): void; } @djclass export class BarMixin extends djbase<Super>() { writeHello(out: string[]) { out.push("-> Bar"); super.writeHello(out); out.push("<- Bar"); } }
finally create an instance and call the writeHello
method
const baz = new Baz(); const data: string[] = []; baz.writeHello(data); console.log(data.join("\n"));
you will get the following output:
-> Baz -> Box -> Bar -> Foo <- Foo <- Bar <- Box <- Baz
Let's take a closer look at the Baz
declaration it uses djbase
to derive
from three mixins and the class is decorated with @djclass
to accomplish the
declaration and make a real constructor.
To allow access to the next sibling method (in terms of multiple inheritance)
Dojo provides this.inherited(arguments)
method but this approach leads to the
problem with 'strict' mode of ES5 and eliminates the type information about a
calling method. This library solves the problem calling inherited/next method by
utilizing super
keyword. Under the hood there are proxy methods generated in
the prototype of the declared class which make calls to this.inherited(...)
method. This technique is compatible with 'strict' mode.
Mixins are declared similar, they also may have the base types although
the most common case is declaring the mixin without any base classes. To allow
the mixin to access the next method declare the interface with
desired methods and use the special form of djbase<Super>()
without arguments.
DjxWidgetBase<Attrs, Events>
This is the base class for the djx widgets. It declares the abstract method
render()
which is used to render the content of the widget, like _TemplatedMixin
.
This class extends dijit/_WidgetBase
and contains logic from _AttachMixin
thus
it is capable to handle data-dojo-attach-*
attributes from the rendered markup.
@djclass export class MyFirstWidget extends djbase(DjxWidgetBase) { render() { return <h1>My first widget</h1>; } }
Markup (.tsx)
Add to your tsconfig.json
the following options
{ "compilerOptions": { "types": [ "@implab/djx", "@implab/dojo-typings" ], "skipLibCheck": true, "experimentalDecorators": true, "jsxFactory": "createElement", "jsx": "react", "target": "ES5", "lib": ["ES2015", "DOM"] } }
Import createElement
into your .tsx
file
import { createElement } from "@implab/djx/tsx";
You are ready to go!
Adding reactive behavior: refs, watch(...) and watchFor(...)
This library adds some reactive traits to update the generated DOM of the widget. Dojo 1.x adds some standard options to deal with dynamic changes:
data-dojo-attach-point
allows to get reference to an element (or a nested widget)- widget attribute mappings, allows to bind widget's property to a property of
the element, referenced by
data-dojo-attach-point
.
The typical implementation of this technique would look like
import { createElement } from "@implab/djx/tsx"; import {djclass, djbase, bind} from "@implab/djx/declare"; @djclass export class MyFirstWidget extends djbase(DjxWidgetBase) { // @bind will generate special attribute mapping // _setCaptionAttr = { node: "captionNode", type: "innerHTML" } @bind({ node: "captionNode", type: "innerHTML" }) caption = "My first widget"; render() { return <h1 data-dojo-attach-point="captionNode"/>; } }
Despite this is a natural way for the dojo it has some disadvantages:
- The compiler doesn't check existence of the attach-point.
- Attribute mappings support only simple mappings, it's difficult to update the complex rendition.
This library helps you to get both goals with special trait watch(...)
import { createElement } from "@implab/djx/tsx"; import { djclass, djbase} from "@implab/djx/declare" @djclass export class MyFirstWidget extends djbase(DjxWidgetBase) { caption = "My first widget"; render() { return <h1>{watch(this,"caption", value => value)}</h1>; } }
In this example we replaced attach-point with simple call to watch
function
which renders string value to text representation (text node). It will create a
rendition which will observe the caption
property of the widget and update its
contents according to the value changes of the property.
The key feature of this approach that the rendering function within watch
may
return a complex rendition.
// inside some widget render() { return <section> {watch(this,"user", value => value && [ <UserInfo user={value}/>, <LogoutButton click={this._logoutClick}/> ])} </section>; } private readonly _logoutClick = () => { /* do logout */ }
The watch
function has two forms:
watch(stateful, prop, render)
- observes the specified property of thedojo/Stateful
object (or widget)watch(observable, render)
- observes the specified observable. It supportsrxjs
or@implab/djx/observable
observables.
The render
callback may return almost anything which will be converted to DOM:
boolean
,null
,undefined
- ignored,string
- converted to text node,array
- converted to DocumentFragment of its elements,- DOM Nodes and widgets are left intact,
- any other kind of value will cause an error.
The watch method allows to observe a single value, for the large sets of data
this isn't suitable well and may lead to performance issues. Dojo provides
observable stores to being able to track individual changes. The library provides
watchFor(observable, render)
method to render observable query results and
handle changes on per item basis.
// inside some widget staff = new Observable(new Memory<Employee>()), getStuff() { return this.staff.query(); } addEmployee(employee: Employee) { this.staff.add(employee); // the rendition will update automatically } render() { return <table> <thead> <tr><th>Name</th><th>Position</th><th>Salary</th></tr> </thead> <tbody> {watchFor(this.getStaff(), ({name, position, salary}) => <tr><td>{name}</td><td>{position}</td><td>{salary}</td></tr> )} </tbody> </table> }