Native JavaScript DOM elements creations
Let’s go through all patterns we would like to use and what needs to be improved for better experience.
Creating element(s) (with custom attributes)
You can create a native DOM element by using the document.createElement(). It is also possible to provide a some attribute(s) declaratively using Object.assign(). More precisely, this way you can sets some IDL.
document.body.append(
+ document.createElement("div")
+);
+console.log(
+ "Emty div is generated inside <body>:",
+ document.body.innerHTML.includes("<div></div>")
+);
+
+document.body.append(
+ Object.assign(
+ document.createElement("p"),
+ { textContent: "Element’s text content.", style: "color: coral;" }
+ )
+);
+To make this easier, you can use the el function. Internally in basic examples, it is wrapper around assign(document.createElement(…), { … }).
import { el, assign } from "https://cdn.jsdelivr.net/gh/jaandrle/deka-dom-el/dist/esm-with-signals.js";
+const color= "lightcoral";
+document.body.append(
+ el("p", { textContent: "Hello (first time)", style: { color } })
+);
+document.body.append(
+ assign(
+ document.createElement("p"),
+ { textContent: "Hello (second time)", style: { color } }
+ )
+);
+The assign function provides improved behaviour of Object.assign(). You can declaratively sets any IDL and attribute of the given element. Function prefers IDL and fallback to the element.setAttribute if there is no writable property in the element prototype.
You can study all JavaScript elements interfaces to the corresponding HTML elements. All HTML elements inherits from HTMLElement. To see all available IDLs for example for paragraphs, see HTMLParagraphElement. Moreover, the assign provides a way to sets declaratively some convenient properties:
- It is possible to sets
data-*/aria-*attributes using object notation. - In opposite, it is also possible to sets
data-*/aria-*attribute using camelCase notation. - You can use string or object as a value for
styleproperty. className(IDL – preffered)/classare ways to add CSS class to the element. You can use string (similarly toclass="…"syntax in HTML) or array of strings. This is handy to concat conditional classes.- Use
classListto toggle specific classes. This will be handy later when the reactivity via signals is beeing introduced. - The
assignalso accepts theundefinedas a value for any property to remove it from the element declaratively. Also for some IDL the corresponding attribute is removed as it can be confusing. For example, natievly the element’sidis removed by setting the IDL to an empty string.
For processing, the assign internally uses assignAttribute and classListDeclarative.
import { assignAttribute, classListDeclarative } from "https://cdn.jsdelivr.net/gh/jaandrle/deka-dom-el/dist/esm-with-signals.js";
+const paragraph= document.createElement("p");
+
+assignAttribute(paragraph, "textContent", "Hello, world!");
+assignAttribute(paragraph, "style", { color: "navy" });
+
+assignAttribute(paragraph, "dataTest1", "v1");
+assignAttribute(paragraph, "dataset", { test2: "v2" });
+
+assignAttribute(paragraph, "ariaLabel", "v1");
+assignAttribute(paragraph, "ariaset", { role: "none" });
+
+
+classListDeclarative(paragraph, {
+ classAdd: true,
+ classRemove: false,
+ classAdd1: 1,
+ classRemove1: 0,
+ classToggle: -1
+});
+
+console.log(paragraph.outerHTML);
+document.body.append(
+ paragraph
+);
+Native JavaScript templating
By default, the native JS has no good way to define HTML template using DOM API:
document.body.append(
+ document.createElement("div"),
+ document.createElement("span"),
+ document.createElement("main")
+);
+console.log(document.body.innerHTML.includes("<div></div><span></span><main></main>"));
+const template= document.createElement("main").append(
+ document.createElement("div"),
+ document.createElement("span"),
+);
+console.log(typeof template==="undefined");
+This library therefore ooverwrites the append method to always return parent element.
import { el } from "https://cdn.jsdelivr.net/gh/jaandrle/deka-dom-el/dist/esm-with-signals.js";
+document.head.append(
+ el("style").append(
+ "tr, td{ border: 1px solid red; padding: 1em; }",
+ "table{ border-collapse: collapse; }"
+ )
+);
+document.body.append(
+ el("p", "Example of a complex template. Using for example nesting lists:"),
+ el("ul").append(
+ el("li", "List item 1"),
+ el("li").append(
+ el("ul").append(
+ el("li", "Nested list item 1"),
+ )
+ )
+ ),
+ el("table").append(
+ el("tr").append(
+ el("td", "Row 1 – Col 1"),
+ el("td", "Row 1 – Col 2")
+ )
+ )
+);
+Creating advanced (reactive) templates and components
Basic components
You can use functions for encapsulation (repeating) logic. The el accepts function as first argument. In that case, the function should return dom elements and the second argument for el is argument for given element.
import { el } from "https://cdn.jsdelivr.net/gh/jaandrle/deka-dom-el/dist/esm-with-signals.js";
+document.head.append(
+ el("style").append(
+ ".class1{ font-weight: bold; }",
+ ".class2{ color: purple; }"
+ )
+);
+document.body.append(
+ el(component, { className: "class2", textContent: "Hello World!" }),
+ component({ className: "class2", textContent: "Hello World!" })
+);
+
+function component({ className, textContent }){
+ return el("div", { className: [ "class1", className ] }).append(
+ el("p", textContent)
+ );
+}
+It is nice to use similar naming convention as native DOM API.