<!DOCTYPE html><html><head><metacharset="utf-8"><metaname="viewport"content="width=device-width, initial-scale=1"><metaname="description"content="Basic concepts of elements modifications and creations."><title>`deka-dom-el` — Elements</title><!--<dde:mark type="component" name="metaAuthor" host="this" ssr/>--><metaname="author"content="Jan Andrle"><linktype="text/plain"rel="author"href="https://jaandrle.github.io/humans.txt"><metaname="generator"content="deka-dom-el"><!--<dde:mark type="component" name="metaTwitter" host="this" ssr/>--><metaname="twitter:card"content="summary_large_image"><metaname="twitter:url"content="https://github.com/jaandrle/deka-dom-el"><metaname="twitter:title"content="deka-dom-el"><metaname="twitter:description"content="A low-code library that simplifies the creation of native DOM elements/components using small wrappers and tweaks."><metaname="twitter:creator"content="@jaandrle"><!--<dde:mark type="component" name="metaFacebook" host="this" ssr/>--><metaname="og:url"content="https://github.com/jaandrle/deka-dom-el"><metaname="og:title"content="deka-dom-el"><metaname="og:description"content="A low-code library that simplifies the creation of native DOM elements/components using small wrappers and tweaks."><metaname="og:creator"content="@jaandrle"><scriptsrc="https://cdn.jsdelivr.net/npm/shiki"defer=""></script><scripttype="module"src="code.js.js"></script><scriptsrc="https://flems.io/flems.html"type="text/javascript"charset="utf-8"></script><linkrel="stylesheet"href="global.css"></head><body><!--<dde:mark type="component" name="page" host="this" ssr/>--><!--<dde:mark type="component" name="simplePage" host="this" ssr/>--><!--<dde:mark type="component" name="header" host="this" ssr/>--><header><h1>`deka-dom-el` — Elements</h1><p>Basic concepts of elements modifications and creations.</p></header><nav><ahref="https://github.com/jaandrle/deka-dom-el"><svgclass="icon"viewBox="0 0 32 32"><!--<dde:mark type="component" name="iconGitHub" host="parentElement" ssr/>--><pathd="M 16,0.395c -8.836,0 -16,7.163 -16,16c 0,7.069 4.585,13.067 10.942,15.182c 0.8,0.148 1.094,-0.347 1.094,-0.77c 0,-0.381 -0.015,-1.642 -0.022,-2.979c -4.452,0.968 -5.391,-1.888 -5.391,-1.888c -0.728,-1.849 -1.776,-2.341 -1.776,-2.341c -1.452,-0.993 0.11,-0.973 0.11,-0.973c 1.606,0.113 2.452,1.649 2.452,1.649c 1.427,2.446 3.743,1.739 4.656,1.33c 0.143,-1.034 0.558,-1.74 1.016,-2.14c -3.554,-0.404 -7.29,-1.777 -7.29,-7.907c 0,-1.747 0.625,-3.174 1.649,-4.295c -0.166,-0.403 -0.714,-2.03 0.155,-4.234c 0,0 1.344,-0.43 4.401,1.64c 1.276,-0.355 2.645,-0.532 4.005,-0.539c 1.359,0.006 2.729,0.184 4.008,0.539c 3.054,-2.07 4.395,-1.64 4.395,-1.64c 0.871,2.204 0.323,3.831 0.157,4.234c 1.026,1.12 1.647,2.548 1.647,4.295c 0,6.145 -3.743,7.498 -7.306,7.895c 0.574,0.497 1.085,1.47 1.085,2.963c 0,2.141 -0.019,3.864 -0.019,4.391c 0,0.426 0.288,0.925 1.099,0.768c 6.354,-2.118 10.933,-8.113 10.933,-15.18c 0,-8.837 -7.164,-16 -16,-16Z"></path></svg>GitHub</a><ahref="./"title="Introducing a library.">1. Introduction</a><ahref="p02-elements"title="Basic concepts of elements modifications and creations."class="current">2. Elements</a><ahref="p03-events"title="Using not only events in UI declaratively.">3. Events and Addons</a><ahref="p04-observables"title="Handling reactivity in UI via observables.">4. Observables and reactivity</a></nav><main><h2>Native JavaScript DOM elements creations</h2><p>Let’s go through all patterns we would like to use and what needs to be improved for better experience.</p><divclass="code"data-js="todo"><!--<dde:mark type="component" name="code" host="parentElement" ssr/>--><codeclass="language-js">// when NPM
</code></div><h3id="h-creating-elements-with-custom-attributes"><!--<dde:mark type="component" name="h3" host="parentElement" ssr/>--><ahref="#h-creating-elements-with-custom-attributes"tabindex="-1">#</a> Creating element(s) (with custom attributes)</h3><p>You can create a native DOM element by using the <ahref="https://developer.mozilla.org/en-US/docs/Web/API/Document/createElement"title="MDN documentation for document.createElement()"><code>document.createElement()</code></a>. It is also possible to provide a some attribute(s) declaratively using <code>Object.assign()</code>. More precisely, this way you can sets some <ahref="https://developer.mozilla.org/en-US/docs/Glossary/IDL"title="MDN page about Interface Description Language"><abbrtitle="Interface Description Language">IDL</abbr></a> also known as a JavaScript property.</p><!--<dde:mark type="component" name="example" host="this" ssr/>--><divid="code-example-1-nkz9lcdhykg"class="example"><!--<dde:mark type="component" name="code" host="parentElement" ssr/>--><codeclass="language-js">document.body.append(
</code></div><script>Flems(document.getElementById("code-example-1-nkz9lcdhykg"),JSON.parse("{\"files\":[{\"name\":\".js\",\"content\":\"document.body.append(\\n\\tdocument.createElement(\\\"div\\\")\\n);\\nconsole.log(\\n\\t\\\"Emty div is generated inside <body>:\\\",\\n\\tdocument.body.innerHTML.includes(\\\"<div></div>\\\")\\n);\\n\\ndocument.body.append(\\n\\tObject.assign(\\n\\t\\tdocument.createElement(\\\"p\\\"),\\n\\t\\t{ textContent: \\\"Element’s text content.\\\", style: \\\"color: coral;\\\" }\\n\\t)\\n);\\n\"}],\"toolbar\":false}"));</script><p>To make this easier, you can use the <code>el</code> function. Internally in basic examples, it is wrapper around <code>assign(document.createElement(…), { … })</code>.</p><!--<dde:mark type="component" name="example" host="this" ssr/>--><divid="code-example-1-13lyjukvr0yk"class="example"><!--<dde:mark type="component" name="code" host="parentElement" ssr/>--><codeclass="language-js">import { el, assign } from "https://cdn.jsdelivr.net/gh/jaandrle/deka-dom-el/dist/esm-with-observables.js";
</code></div><script>Flems(document.getElementById("code-example-1-13lyjukvr0yk"),JSON.parse("{\"files\":[{\"name\":\".js\",\"content\":\"import { el, assign } from \\\"https://cdn.jsdelivr.net/gh/jaandrle/deka-dom-el/dist/esm-with-observables.js\\\";\\nconst color= \\\"lightcoral\\\";\\ndocument.body.append(\\n\\tel(\\\"p\\\", { textContent: \\\"Hello (first time)\\\", style: { color } })\\n);\\ndocument.body.append(\\n\\tassign(\\n\\t\\tdocument.createElement(\\\"p\\\"),\\n\\t\\t{ textContent: \\\"Hello (second time)\\\", style: { color } }\\n\\t)\\n);\\n\"}],\"toolbar\":false}"));</script><p>The <code>assign</code> function provides improved behaviour of <code>Object.assign()</code>. You can declaratively sets any IDL and attribute of the given element. Function prefers IDL and fallback to the <code>element.setAttribute</code> if there is no writable property in the element prototype.</p><p>You can study all JavaScript elements interfaces to the corresponding HTML elements. All HTML elements inherits from <ahref="https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement">HTMLElement</a>. To see all available IDLs for example for paragraphs, see <ahref="https://developer.mozilla.org/en-US/docs/Web/API/HTMLParagraphElement">HTMLParagraphElement</a>. Moreover, the <code>assign</code> provides a way to sets declaratively some convenient properties:</p><ul><li>It is possible to sets <code>data-*</code>/<code>aria-*</code> attributes using object notation.</li><li>In opposite, it is also possible to sets <code>data-*</code>/<code>aria-*</code> attribute using camelCase notation.</li><li>You can use string or object as a value for <code>style</code> property.</li><li><code>className</code> (IDL – preffered)/<code>class</code> are ways to add CSS class to the element. You can use string (similarly to <code>class="…"</code> syntax in HTML) or array of strings. This is handy to concat conditional classes.</li><li>Use <code>classList</code> to toggle specific classes. This will be handy later when the reactivity via observables is beeing introduced.</li><li>The <code>assign</code> also accepts the <code>undefined</code> as 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. <em>For example, natievly the element’s <code>id</code> is removed by setting the IDL to an empty string.</em></li><li>You can use <code>=</code> or <code>.</code> to force processing given key as attribute/property of the element.</li></ul><p>For processing, the <code>assign</code> internally uses <code>assignAttribute</code> and <code>classListDeclarative</code>.</p><!--<dde:mark type="component" name="example" host="this" ssr/>--><divid="code-example-1-iro9ncxa4bc"class="example"><!--<dde:mark type="component" name="code" host="parentElement" ssr/>--><codeclass="language-js">import { assign, assignAttribute, classListDeclarative } from "https://cdn.jsdelivr.net/gh/jaandrle/deka-dom-el/dist/esm-with-observables.js";
</code></div><script>Flems(document.getElementById("code-example-1-b6a1hbrxh7s"),JSON.parse("{\"files\":[{\"name\":\".js\",\"content\":\"document.body.append(\\n\\tdocument.createElement(\\\"div\\\"),\\n\\tdocument.createElement(\\\"span\\\"),\\n\\tdocument.createElement(\\\"main\\\")\\n);\\nconsole.log(document.body.innerHTML.includes(\\\"<div></div><span></span><main></main>\\\"));\\nconst template= document.createElement(\\\"main\\\").append(\\n\\tdocument.createElement(\\\"div\\\"),\\n\\tdocument.createElement(\\\"span\\\"),\\n);\\nconsole.log(typeof template===\\\"undefined\\\");\\n\"}],\"toolbar\":false}"));</script><p>This library therefore overwrites the <code>append</code> method of created elements to always return parent element.</p><!--<dde:mark type="component" name="example" host="this" ssr/>--><divid="code-example-2-iro9ncxa4bc"class="example"><!--<dde:mark type="component" name="code" host="parentElement" ssr/>--><codeclass="language-js">import { el } from "https://cdn.jsdelivr.net/gh/jaandrle/deka-dom-el/dist/esm-with-observables.js";
</code></div><script>Flems(document.getElementById("code-example-2-iro9ncxa4bc"),JSON.parse("{\"files\":[{\"name\":\".js\",\"content\":\"import { el } from \\\"https://cdn.jsdelivr.net/gh/jaandrle/deka-dom-el/dist/esm-with-observables.js\\\";\\ndocument.head.append(\\n\\tel(\\\"style\\\").append(\\n\\t\\t\\\"tr, td{ border: 1px solid red; padding: 1em; }\\\",\\n\\t\\t\\\"table{ border-collapse: collapse; }\\\"\\n\\t)\\n);\\ndocument.body.append(\\n\\tel(\\\"p\\\", \\\"Example of acomplex template. Using for example nesting lists:\\\"),\\n\\tel(\\\"ul\\\").append(\\n\\t\\tel(\\\"li\\\", \\\"List item 1\\\"),\\n\\t\\tel(\\\"li\\\").append(\\n\\t\\t\\tel(\\\"ul\\\").append(\\n\\t\\t\\t\\tel(\\\"li\\\", \\\"Nested list item 1\\\"),\\n\\t\\t\\t)\\n\\t\\t)\\n\\t),\\n\\tel(\\\"table\\\").append(\\n\\t\\tel(\\\"tr\\\").append(\\n\\t\\t\\tel(\\\"td\\\", \\\"Row 1 – Col 1\\\"),\\n\\t\\t\\tel(\\\"td\\\", \\\"Row 1 – Col 2\\\")\\n\\t\\t)\\n\\t)\\n);\\n\\nimport { chainableAppend } from \\\"https://cdn.jsdelivr.net/gh/jaandrle/deka-dom-el/dist/esm-with-observables.js\\\";\\n/** @param {keyof HTMLElementTagNameMap} tag */\\nconst createElement= tag=> chainableAppend(document.createElement(tag));\\ndocument.body.append(\\n\\tcreateElement(\\\"p\\\").append(\\n\\t\\tcreateElement(\\\"em\\\").append(\\n\\t\\t\\t\\\"You can also use `chainableAppend`!\\\"\\n\\t\\t)\\n\\t)\\n);\\n\"}],\"toolbar\":false}"));</script><h3id="h-basic-state-less-components"><!--<dde:mark type="component" name="h3" host="parentElement" ssr/>--><ahref="#h-basic-state-less-components"tabindex="-1">#</a> Basic (state-less) components</h3><p>You can use functions for encapsulation (repeating) logic. The <code>el</code> accepts function as first argument. In that case, the function should return dom elements and the second argument for <code>el</code> is argument for given element.</p><!--<dde:mark type="component" name="example" host="this" ssr/>--><divid="code-example-1-320zz4y072o"class="example"><!--<dde:mark type="component" name="code" host="parentElement" ssr/>--><codeclass="language-js">import { el } from "https://cdn.jsdelivr.net/gh/jaandrle/deka-dom-el/dist/esm-with-observables.js";
</code></div><script>Flems(document.getElementById("code-example-1-320zz4y072o"),JSON.parse("{\"files\":[{\"name\":\".js\",\"content\":\"import { el } from \\\"https://cdn.jsdelivr.net/gh/jaandrle/deka-dom-el/dist/esm-with-observables.js\\\";\\ndocument.head.append(\\n\\tel(\\\"style\\\").append(\\n\\t\\t\\\".class1{ font-weight: bold; }\\\",\\n\\t\\t\\\".class2{ color: purple; }\\\"\\n\\t)\\n);\\ndocument.body.append(\\n\\tel(component, { className: \\\"class2\\\", textContent: \\\"Hello World!\\\" }),\\n\\tcomponent({ className: \\\"class2\\\", textContent: \\\"Hello World!\\\" })\\n);\\n\\nfunction component({ className, textContent }){\\n\\treturn el(\\\"div\\\", { className: [ \\\"class1\\\", className ] }).append(\\n\\t\\tel(\\\"p\\\", textContent)\\n\\t);\\n}\\n\"}],\"toolbar\":false}"));</script><p>As you can see, in case of state-less/basic components there is no difference between calling component function directly or using <code>el</code> function.</p><pclass="notice">It is nice to use similar naming convention as native DOM API. This allows us to use <ahref="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Destructuring_assignment"title="Destructuring assignment | MDN">the destructuring assignment syntax</a> and keep track of the native API (things are best remembered through regular use).</p><h3id="h-creating-non-html-elements"><!--<dde:mark type="component" name="h3" host="parentElement" ssr/>--><ahref="#h-creating-non-html-elements"tabindex="-1">#</a> Creating non-HTML elements</h3><p>Similarly to the native DOM API (<ahref="https://developer.mozilla.org/en-US/docs/Web/API/Document/createElementNS"title="MDN"><code>document.createElementNS</code></a>) for non-HTML elements we need to tell JavaScript which kind of the element to create. We can use the <code>elNS</code> function:</p><!--<dde:mark type="component" name="example" host="this" ssr/>--><divid="code-example-1-bcjydb50gdc"class="example"><!--<dde:mark type="component" name="code" host="parentElement" ssr/>--><codeclass="language-js">import { elNS, assign } from "https://cdn.jsdelivr.net/gh/jaandrle/deka-dom-el/dist/esm-with-observables.js";
</code></div><script>Flems(document.getElementById("code-example-1-bcjydb50gdc"),JSON.parse("{\"files\":[{\"name\":\".js\",\"content\":\"import { elNS, assign } from \\\"https://cdn.jsdelivr.net/gh/jaandrle/deka-dom-el/dist/esm-with-observables.js\\\";\\nconst elSVG= elNS(\\\"http://www.w3.org/2000/svg\\\");\\nconst elMath= elNS(\\\"http://www.w3.org/1998/Math/MathML\\\");\\ndocument.body.append(\\n\\telSVG(\\\"svg\\\"), // see https://developer.mozilla.org/en-US/docs/Web/SVG and https://developer.mozilla.org/en-US/docs/Web/API/SVGElement\\n\\telMath(\\\"math\\\") // see https://developer.mozilla.org/en-US/docs/Web/MathML and https://developer.mozilla.org/en-US/docs/Web/MathML/Global_attributes\\n);\\n\\nconsole.log(\\n\\tdocument.body.innerHTML.includes(\\\"<svg></svg><math></math>\\\")\\n)\\n\"}],\"toolbar\":false}"));</script><divclass="notice"><!--<dde:mark type="component" name="mnemonicUl" host="parentElement" ssr/>--><h3id="h-mnemonic"><!--<dde:mark type="component" name="h3" host="parentElement" ssr/>--><ahref="#h-mnemonic"tabindex="-1">#</a> Mnemonic</h3><ul><li><code>assign(<element>, ...<idl-objects>): <element></code> — assign properties to the element</li><li><code>el(<tag-name>, <primitive>)[.append(...)]: <element-from-tag-name></code> — simple element containing only text</li><li><code>el(<tag-name>, <idl-object>)[.append(...)]: <element-from-tag-name></code> — element with more properties</li><li><code>el(<function>, <function-argument(s)>)[.append(...)]: <element-returned-by-function></code> — using component represented by function</li><li><code>el(<...>, <...>, ...<addons>)</code> — see following page</li><li><code>elNS(<namespace>)(<as-el-see-above>)[.append(...)]: <element-based-on-arguments></code> — typically SVG elements</li></ul></div><divclass="prevNext"><!--<dde:mark type="component" name="prevNext" host="parentElement" ssr/>--><arel="prev"href="./"title="Introducing a library."><!--<dde:mark type="component" name="pageLink" host="parentElement" ssr/>-->Introduction (previous)</a><arel="next"href="p03-events"title="Using not only events in UI declaratively."><!--<dde:mark type="component" name="pageLink" host="parentElement" ssr/>-->(next) Events and Addons</a></div></main></body></html>
