htmr  

> Simple and lightweight (< 2kB) HTML string to react element conversion library

Install

``sh
$ yarn add htmr

or

$ npm install htmr --save
`

Usage

Use the default export, and pass HTML string.

`js
import React from 'react';
import htmr from 'htmr';

function HTMLComponent() {
return htmr('

No more dangerouslySetInnerHTML

');
}
`

The API also accepts second argument options containing few optional fields. Below are their default values:

`js
const options = {
transform: {},
preserveAttributes: [],
dangerouslySetChildren: ['style'],
};
htmr(html, options);
`

$3

transform accepts key value pairs, that will be used to transforms node (key) to custom component (value). You can use it to render specific tag name with custom component. For example: component with
predefined styles like
styled-components.

`js
import React from 'react';
import htmr from 'htmr';
import styled from 'styled-components';

const Paragraph = styled.p
font-family: Helvetica, Arial, sans-serif;
line-height: 1.5;
;

const transform = {
p: Paragraph,
// you can also pass string for native DOM node
a: 'span',
};

function TransformedHTMLComponent() {
// will return {'Custom component'}
return htmr('

Custom component

', { transform });
}
`

You can also provide default transform using underscore _ as property name.

This can be useful if you want to do string preprocessing (like removing all whitespace), or rendering HTML as native view in react-native:

`js
import React from 'react';
import { Text, View } from 'react-native';

const transform = {
div: View,
_: (node, props, children) => {
// react-native can't render string without component
// we can test text node by checking component props, text node won't have them
if (typeof props === 'undefined') {
// use key because it's possible that is rendered
// inside array as sibling
return {node};
}

// render unknown tag using
// ideally you also filter valid props to
return {children};
},
};

function NativeHTMLRenderer(props) {
return htmr(props.html, { transform });
}
`

$3

By default htmr will convert HTML attributes to camelCase because that's what React uses. You can override this behavior by passing preserveAttributes options. Specify array of string / regular expression to test which attributes you want to preserve.

For example you want to make sure ng-if, v-if and v-for to be rendered as is

`js
htmr(html, { preserveAttributes: ['ng-if', new RegExp('v-')] });
`

$3

By default htmr will only render children of style tag inside dangerouslySetInnerHTML due to security reason. You can override this behavior by passing array of HTML tags if you want the children of the tag to be rendered dangerously.

`js
htmr(html, { dangerouslySetChildren: ['code', 'style'] });
`

Note that if you still want style tag to be rendered using dangerouslySetInnerHTML, you still need to include it in the array.

Multiple children

You can also convert HTML string which contains multiple elements. This returns
an array, so make sure to wrap the output inside other component such as div, or
use React 16.

`js
import React from 'react';
import htmr from 'htmr';

const html =

This string

Contains multiple html tags

as sibling

;

function ComponentWithSibling() {
// if using react 16, simply use the return value because
// v16 can render array
return htmr(html);
// if using react 15 and below, wrap in another component
return

{htmr(html)}

;
}
`

Typescript, htmr transform and Web Components

If you're using htmr to transform custom elements in a typescript code, you'll get type error because custom element is not defined as valid property. To work around this, you can define the mapping in a separate object, and typecast as any while spreading in transform object:

`ts
import { ElementType } from 'react';
import { HtmrOptions } from 'htmr';

const customElementTransform: Record = {
'virtual-scroller': VirtualScroller,
};

const options: HtmrOptions = {
transform: {
a: Anchor,
...(customElementTransform as any),
},
};

htmr(html, options);
`

Use Cases

This library was initially built to provides easy component mapping between HTML
string and React component. It's mainly used to render custom
component from HTML string returned from an API. This library **prioritize
file size and simple API** over full HTML conversion coverage and other features
like JSX parsing or flexible node traversal.

That's why I've decided to not implement some features (see Trade Off
section below). If you feel like you need more features that's not possible
using this library, you can check out some related projects below.

Trade Off

- Inline event attributes (onclick="" etc) are not supported due to unnecessary complexity
- htmr use native browser HTML parser when run in browser instead of using custom parser. Due to how browser HTML parser works, you can get weird result if you supply "invalid" html, for example div inside p element like


- Script tag is not rendered using dangerouslySetInnerHTML by default due to security. You can opt in by using dangerouslySetChildren
- Style tag renders it children using dangerouslySetInnerHTML` by default. You can also reverse this behavior using same method.

Related projects

HTML to react element:

- html-to-react
- react-html-parser
- html-react-parser
- react-render-html

HTML (page) to react component (file/string):

- html-to-react-components
- react-magic

License

MIT