diff --git a/documentation/render.md b/documentation/render.md new file mode 100644 index 0000000..555a9a2 --- /dev/null +++ b/documentation/render.md @@ -0,0 +1,247 @@ +# Rendering DOM nodes using `render.js` + +```js +import {html} from "nyooom/render.js" +``` + +A functional-friendly helper library for procedural DOM generation and templating, with support for reactive state objects. + +## Summary + +```js +html.button( + "Click Me!", + { + class: "primary", + click({target}) { + console.log("User clicked", target) + } + }, + button => { console.log("Created", button) } +) +``` + +* elements as factory functions `content -> element` +* content as arguments or in arrays +* attributes in object arguments +* style, dataset, shadow root, etc. as magic attributes +* events as function attributes +* initialisers as `any -> void` functions + +## Interface / Examples + +### Basic DOM generation + +Accessing the `html` proxy with any string key returns a new node generator function. +When called this function will generate a DOM node (HTML Tag). +The name of the function becomes the tag name of the node. + +```js +html.div() +``` + +Content and attributes can be set via the function arguments: +Strings and DOM nodes are inserted as children, while other objects (except for some special cases) have their key-value pairs turned into attribute-value pairs on the + +```js +html.div("Big Text", {style: "font-size: 1.4em"}) +``` + +Arrays are iterated and their values treated as arguments. +This works both for inserting children and setting attributes. + +```js +const content = [" ps: hi", {class: "title"}] +html.h1({id: "main-heading"}, "Heading", content) +``` + +Function arguments are treated differently depending on their length:] +Functions with **no** named parameters are called, and their return value is then evaluated just like an argument to the generator. + +All other functions are (immediately) called with the newly created node as their first and only argument. +These can be used to initialise the new node in a point-free style. + +```js +const hello = () => html.bold("Hello, World!") +const init = node => console.log("Initialising", node) +html.div(hello, init) +``` + +Nested tags can be generated with nested function calls. +When properly formatted, this means simpler templates will have the same structure as if written in HTML (sans those pesky closing tags). + +```js +html.div( + html.p( + html.b("Bold Text") + ) +) +``` + +### Attribute Processing + +For convenience, arrays assigned as attributes will be joined with spaces: + +```js +html.a({class: ["button", "important"]}) +``` + +Assigning a function as an attribute will instead attach it as an event listener: + +```js +html.button("Click me!", {click: event => { + alert("You clicked the button.") +}}) +``` + +The special `style` property can be set to an object and its key/value pairs will be inserted as CSS properties on the element's `style` object. + +```js +const style = { color: "salmon" } +html.span("Salmon", { style }) +``` + +The special property `shadowRoot` will attach a shadow-DOM to the element if none is present and append its content to the shadow root. +Arrays are iterated over and their elements appended individually. + +```js +html.div({ + shadowRoot = ["Hello, ", html.b("World"), "!"] +}) +``` + +The `dataset` property will add its key/value pairs to the new node's `dataset`, +as a more convenient alternative to setting individual `data-` attributes. + +```js +const dataset = { foo: "bar" } +const div = html.div({dataset}) +console.log(dataset.foo === div.dataset.foo) +console.log(div.getAttribute("data-foo") === "bar") +``` + +### Reactivity + +Nyooom supports reactivity through a simple protocol: + +Observable objects identify themselves with the `observable` attribute, +which must return a truthy value. + +Observables are expected to expose a `value` attribute that is both readable and writeable, +and to emit a "change" event whenever its vale has changed. + +Observables can be passed to nyooom's node functions as both +attribute values (values in an object) or +child elements (direct arguments or in an array). + +#### Reactive Children + +Passing an observable as a child element will attempt to insert its current +value into the new node as if it was passed in directly, but will also hook into +the observable to replace the value when the state changes. + +```js +const state = new Observable.value(0) + +const button = html.button(state, { + click(event) { state.value++ } +}) +``` + +Note that to keep the replacement logic simple, it is not currently possible to +insert use document fragments, as these could insert several top-level children +into a component that would then all have to be replaced. When an observable +contains or changes to a document fragment, nyooom will raise an error. + +Before replacing an element, a `"replace"` event is emitted from the old +element. This event bubbles and is cancelable, and can thus be used both to +completely prevent the replacement according to custom logic, to alter or +initialise the new element before it is inserted, or even to modify the old +object instead of replacing it. + +#### Reactive Attributes + +Passing an observable as an object value will, likewise, treat its value as the +attribute value, and update it whenever the state's value changes. + +```js +const state = new Observable.value(0) + +const input_1 = html.input({ type: "number", value: state }) +const input_2 = html.input({ type: "number", value: state }) +``` + +## Helpers + +### Empty Values + +Nyooom will produce a warning when it encounters `undefined` as an argument to a +node factory, and skip it. + +When completely ommitting the argument would make code more complicated, the +`nothing` export can be used instead, and will be completely ignored by nyooom: + +```js +import {html, nothing} from "nyooom/render" + +const value = undefined + +html.div(value ? html.p(value) : nothing) //
+``` + +### Event Handlers + +Event handlers often need to call `preventDefault()` and `stopPropagation()` on +the event. To save a bit of typing, the wrapper functions `noDefault` and +`noPropagation` take a function `event => void` and wrap it in a function that +first calls the corresponding method on the event: + +```js +html.form( + html.button("Click me!", click: noDefault(() => console.log("Clicked!"))) +) +``` + +### DOM-Fragments + +The `fragment` helper function collects a list of DOM nodes from its arguments +into a new document fragment, so they can more easily be processed as a group +and inserted elsewhere. + +```js +import {fragment} from "nyooom/render" + +const f = fragment(html.p("paragraph 1"), html.p("paragraph 1")) +document.body.append(f.cloneNode(true)) +``` + +### Text + +The `text` helper function operates in two modes: When a string is provided, it +outputs a `TextNode`. This acts the same as `document.createTextNode`, except it +won't error for `undefined` and instead simply return an empty text node. + +When used as a template literal, it will return a document template containing a +list of text nodes. HTML-Elements can be interpolated into these fragments and +will be inserted into the template. + +```js +import {text} from "nyooom/render" + +const t = text`Hello, ${html.b("World")}!` +``` + +## Extending + +The Nyooom renderer is built in a modular way that allows for easy extending: + +The most generic functionality like the `proxy()` method is implemented in the +`Renderer` class. + +This is extended by the `DomRenderer` class which defines how +elements are created inside the browser or a compatible DOM implementation. + +The DomHtmlRenderer defines a `camelCase` to `snake-case` conversion for node +names and a list of magic node names to be handled differently. + +The `DomSvgRenderer` creates DOM nodes in the SVG namespace.