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htmlhammer

Write HTML with JavaScript using real HTML tag names.

Why?

String literals tend to get messy and unreadable
Maybe you don’t want or need JSX
HyperScript is ok, but you would like to avoid manually writing HTML tag names
Make writing HTML in JavaScript feel almost like writing it in .html file
Make writing HTML in JavaScript dead simple and intuitive but keeping all the JavaScript’s power

Install

github

Latest version: npm install git+https://github.com/vsmid/htmlhammer.git --save
Specific version: npm install git+https://github.com/vsmid/htmlhammer.git\#1.0.0 --save

npmjs

npm i htmlhammer

unpkg

<!-- Latest version CJS -->
<script src="https://unpkg.com/htmlhammer"></script>

<!-- Version 1.0.1 CJS -->
<script src="https://unpkg.com/htmlhammer@1.0.1"></script>

<!-- Latest version ESM -->
<script type="module">
    import { div } from "https://unpkg.com/htmlhammer?module";
</script>

<!-- Latest version single file IIFE -->
<script src="https://unpkg.com/htmlhammer/htmlhammer.js"></script>

<!-- Latest version minified single file IIFE -->
<script src="https://unpkg.com/htmlhammer/htmlhammer.min.js"></script>

For specific versions use url format: unpkg.com/:package@:version/:file. See UNPKG for more info.

Importing and using htmlhammer

// In html
<script src="./htmlhammer.js"></script>
const { div } = htmlhammer;

// In modules
const { div, a, h1 } = require("htmlhammer").default;
import { div, a, h1 } from "htmlhammer";

Using htmlhammer

Supported HTML tags/elements

See the list on MDN. Tags/elements marked as obsolete/deprecated are not supported.

Signature

// Function name htmltagname is one of supported HTML tag/elements, e.g. div, a, h1, table etc.
// Since version 2.3.0 attributesAndProperties parameter is optional
htmltagname((attributesAndProperties = {}), ...children);

Parameters:

attributesAndProperties - JSON object where key is the name of the element’s attribute/property (e.g. id, name, style, onclick, or custom attribute/property etc. ) and value is the new attribute/property value. Difference between defining an attribute and property is that property value must always be one of function, instance of class, array or json object. This rule does not apply to reserved element attributes/properties and style.
children - element or elements to be appended to parent element. Can be string, number, another HTMLElement created regularly or by htmlhammer, function returning one of the previously stated types etc.

Returns:

An array of HTMLElement or a single HTMLElement.

Code sample

let items = [{ value: 1 }, { value: 2 }];

document.body.append(
    div(
        { style: { color: "red" } },
        h1("I am the title"),
        a({ href: "#" }, "Click me!"),
        table(
            tr({ $for: items }, (item) => td(item.value))
        )
    )
);

String as HTML

If you have HTML in string format and you would like for it to be added to element as HTML you should wrap it in HtmlString class. This is useful when you want to inject an already generated HTML in string format to an element ( e.g. HTML content received from REST service).

import { div, HtmlString } from "./esm/index.js";

const html = "<h1>Hello World!</h1>";

document.body.append(
    div(new HtmlString(html)) // Without HTMLString wrapper, html content would be treated as text content hence text node would be created
);

Version 2.1.0 introduced a new attribute handler $apply which allows you to create inline element in any way you like.

const RawHtml = (data) => (el) => (el.innerHTML = data);

document.body.append(
    div(
        span({ $apply: RawHtml("<h1>Hello World!</h1>") })
    )
);

For more complex and complete example check index.html.

Reserved element attributes/properties

`$for` - creating multiple elements of the same type

// Creates three elements of type div, <div>1</div>, <div>2</div>, <div>3</div>
// index parameter is optional
// item = 1, index = 0
// item = 2, index = 1
// item = 3, index = 2
div({ $for: [1, 2, 3] }, (item, index) => item);

`$if` - conditionally create element

div({ $if: true }, "I am created");
div({ $if: () => true }, "I am created");

// Create only items with value > 2
div({ $for: [1, 2, 3], $if: (item) => item > 2 }, (item) => item);

`$ref` - reference created element

A key under which element will be stored must be an object!

const { div, ref, setRef } = htmlhammer;

// Reference by object
let obj = {};

// Prior to 2.2.0
let element = div({ $ref: setRef(obj) }, "Hello World!");

// Version 2.2.0 allows ref to be set just by passing an object reference
let element = div({ $ref: obj }, "Hello World!");

console.log(ref(obj) === element);

// Manually assigning id if the same object is used for multiple references
let person = new Person("Lena", 0);

div({ $ref: setRef(person, "name") }, person.name);
div({ $ref: setRef(person, "age") }, person.age);

console.log(ref(person, "name"));
console.log(ref(person, "age"));

// If used in combination with $for do not set object reference manually because it will automatically be set to the list item value
element = div(
    { $for: [{ v: 1 }, { v: 2 }, { v: 3 }], $ref: setRef },
    "Hello World!"
);

`$apply` - apply anything to an element

Use this attribute to apply anything to an element. This gives you the full power of JavaScript Element API mixed within htmlhammer's inline element creation. This can also be ideal for sharing style, logic, event handlers etc. across multiple components/elements. $apply can be given as a function which receives element or an array of such functions.

const RedText = (el) => (el.style.color = "red");

// Function which can replace new HtmlString("<h1>Hello</h1>")
const HTMLContent = (data) => (el) => (el.innerHTML = data);

// Valid usages
div({ $apply: RedText });
div({ $apply: [RedText, HTMLContent("<h1>Hello</h1>")] });

Setting on-event actions

Event names are case-sensitive. For each event use corresponding element’s event name.

// Defines element's onclick event function
a({ onclick: (e) => alert("Clicked!") }, "Click me");
// Defines plain function on element, will not trigger on click
a({ onClick: (e) => alert("Clicked!") }, "Click me");

Setting CSS

CSS is given in the form of JSON object when using element’s style attribute or HTMLStyleElement when using HTML tag style.

// Global, using HTMLStyleElement
document.head.append(
    style(`
      body {
        font-size: 12px;
      }`
    )
);

// Inline, using style attribute
div({ style: { color: "red", fontSize: "12px" } }, "Hello World!");

When setting style attribute values, use corresponding JavaScript CSS property names. See MDN.

Custom child appender

Version 2.0.0 introduced option to provide a custom way of how child element is appended to parent element. Use case for this can be seen in HtmlString appender where raw html in the form of string needs to inserted to DOM element. For this to happen, element’s insertAdjacentHTML method is used instead of default append method. See how HtmlString appender is implemented in appenders.js.

Custom elements

Method signature

customElement(tagName, provider, type)

tagName - custom element tag name
provider - plain JS object with lifecycle functions and props implementations. See under Lifecycle and reserved props.
type - optional, function reference to one of htmlhammer’s functions (e.q. div, a, table etc.). Use when you want to extend existing html element, e.q. HTMLDivElement.

Lifecycle and reserved props

postConstruct
connectedCallback
disconnectedCallback
attributeChangedCallback
adoptedCallback
observedAttributes

Differences to the specification:

postConstruct - think of it as a constructor.
observedAttributes - an array of strings (names of the observed attributes)

Create generic custom element

Using only htmlhammer

const { customElement } = htmlhammer; // or use ES6 import

const yetiCustom = customElement("yeti-custom", {
    connectedCallback() {
        console.log("Generic custom element created!");
    }
});

document.body.append(yetiCustom());

Using htmlhammer and html

<script>
    const { customElement } = htmlhammer; // or use ES6 import

    const yetiCustom = customElement("yeti-custom", {
        connectedCallback() {
            console.log("Generic custom element created!");
        }
    });
</script>

<yeti-custom></yeti-custom>

Create specialized custom element

Using only htmlhammer

const { div, customElement } = htmlhammer; // or use ES6 import

const yetiDiv = customElement("yeti-div", {
    connectedCallback() {
        console.log("Generic custom element created!");
    }
}, div);

document.body.append(div({ is: "yeti-div" }));

Using htmlhammer and html

<script>
    const { div, customElement } = htmlhammer; // or use ES6 import

    const yetiDiv = customElement("yeti-div", {
        connectedCallback() {
            console.log("Generic custom element created!");
        }
    }, div);
</script>

<div is="yeti-div"></div>

Setting shadow dom

Inside custom element

const { customElement } = htmlhammer; // or use ES6 import

const yetiCustom = customElement("yeti-custom", {
    connectedCallback() {
        this.attachShadow({ mode: "open" });
    }
});

As htmlhammer attribute

yetiCustom({ shadowRoot: { mode: "open" } }, "Hello from Generic CustomElement");

Setting styles

Inside custom element

const { style, customElement } = htmlhammer; // or use ES6 import

const yetiCustom = customElement("yeti-custom", {
    connectedCallback() {
        this.attachShadow({ mode: "open" });
        this.shadowRoot.append(style(`:host { font-weight: bold;}`));
    }
});

As htmlhammer attribute

yetiCustom({ shadowRoot: { mode: "open", stylesheets: [style(`:host {color: red;}`)] } },
    "Hello from Generic CustomElement");

Conventions

Conventions apply only to the provider(see under Method signature).

Function starting with capital letter - binds function to context (custom element instance)
Property starting with capital letter - receives get/set methods
Property not starting with capital letter - receives only get method
Property is named the same as observed attribute - property will reflect attribute

Project’s NPM scripts

`test` - run tests

npm test

`coverage` - create and print test coverage report to console

npm run coverage

`coverage:file` - create and print test coverage report to test-coverage-report.txt file

npm run coverage:file

`build` - build project

npm run build