rehype-add-classes [![Build Status][travis-badge]][travis]

Add classes by selector to elements with [rehype][rehype].

Useful for adding:

* hljs class to

 tag when converting markdown code snippets to html
* Required css framework classes to elements (for example using [Bulma][bulma])
Installation
[npm][]:
``bash
npm install rehype-add-classes
`
Usage
Consider the following example.js with rehype processor (or use unified) setup as follows:
`javascript
import rehype from 'rehype';
import vfile from 'to-vfile';
import addClasses from 'rehype-add-classes';
const processor = rehype()
    .data('settings', { fragment: true })
    .use(addClasses, {
        pre: 'hljs',
        'h1,h2,h3': 'title',
        h1: 'is-1',
        h2: 'is-2',
        p: 'one two'
    });
const html = 
    

    
header

    
sub 1

    
sub 2

    

;
const { contents } = processor.processSync(vfile({ contents: html }));
console.log(contents);
`
Now, running node example.js yields:
`console
    

    
header

    
sub 1

    
sub 2

    

`
API
$3
Add to rehype or unified pipeline with .use, where additions is an object
with keys that are the css selectors and the values are a string to add to 
the class of each found node.
Example:
`js
{
    pre: 'hljs',         
    'h1,h2,h3': 'title',
    h1: 'is-1',         
    h2: 'is-2',         
    p: 'one two'
}       
`
* Results are cumulative: 

* value is added to existing classes: 
sub 2

* Whole of string indicated by value is added: 
This library uses hast-util-select` under the hood. See [these details][supported-selectors]
for supported selectors.
License
[MIT][license] ©2018 [Marty Nelson][author]
[author]: https://github.com/martypdx
[bulma]: https://bulma.io
[npm]: https://docs.npmjs.com/cli/install
[license]: LICENSE
[rehype]: https://github.com/rehypejs/rehype
[supported-selectors]: https://github.com/syntax-tree/hast-util-select#support
[travis-badge]: https://img.shields.io/travis/martypdx/rehype-add-classes.svg
[travis]: https://travis-ci.org/martypdx/rehype-add-classes