@microflash/fenceparser
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A metadata parser for code fences in markdown
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Markdown
# fenceparser
[](https://www.npmjs.com/package/@microflash/fenceparser)
[](https://github.com/Microflash/fenceparser/actions/workflows/regression.yml)
[](./LICENSE.md)
A metadata parser for code fences in markdown
- [What’s this?](#whats-this)
- [Install](#install)
- [Use](#use)
- [API](#api)
- [Options](#options)
- [Syntax](#syntax)
- [Examples](#examples)
- [Example: single range](#example-single-range)
- [Example: multiple ranges](#example-multiple-ranges)
- [Example: ranges with custom annotations](#example-ranges-with-custom-annotations)
- [Example: key-value pairs](#example-key-value-pairs)
- [Example: customizing the default range's key](#example-customizing-the-default-ranges-key)
- [Development](#development)
- [License](#license)
## What’s this?
Many markdown processors can parse the language token associated with a code fence. `fenceparser` is meant for parsing other metadata besides language token. It supports
- ranges, (e.g., `{1} {3, 7} ins{9..11, 88} del{90, 101..167}`) and
- key-value pairs (e.g., `caption='Hello, World'`)
## Install
This package is [ESM only](https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c).
In Node.js (version 12.20+, 14.14+, or 16.0+), install with [npm](https://docs.npmjs.com/cli/install):
```sh
npm install @microflash/fenceparser
```
In Deno, with [esm.sh](https://esm.sh/):
```js
import fenceparser from "https://esm.sh/@microflash/fenceparser";
```
In browsers, with [esm.sh](https://esm.sh/):
```html
<script type="module">
import fenceparser from "https://esm.sh/@microflash/fenceparser?bundle";
</script>
```
## Use
Say, you have the following code fence
```
```js {1} {3, 7} {9..11, 88} {90, 101..112} text-color='--text-default' syntax_theme="nord" css=`{ *: { display: none }}`
```
[remark](https://github.com/remarkjs/remark) will provide the `meta` and `lang` for the above code fence.
```json
{
"lang": "js",
"meta": "{1} {3, 7} {9..11, 88} {90, 101..112} text-color='--text-default' syntax_theme=\"nord\" css=`{ *: { display: none }}`"
}
```
Use the `fenceparser` to parse the `meta` as follows.
```js
import FenceParser from "@microflash/fenceparser";
const parser = new FenceParser();
console.log(parser.parse("{1} {3, 7} {9..11, 88} {90, 101..112} text-color='--text-default' syntax_theme=\"nord\" css=`{ *: { display: none }}`"));
```
Running the above example yields.
```js
{
'text-color': '--text-default',
syntax_theme: 'nord',
css: '{ *: { display: none }}',
highlight: [
1, 3, 7, 9, 10, 11, 88,
],
ins: [
90, 101, 102, 103, 104, 105,
106, 107, 108, 109, 110, 111,
112,
]
}
```
## API
The default export is `FenceParser` class.
### Options
The following options are available. All of them are optional.
- `rangeKey` (default: `highlight`): specifies the key for the default range of numbers
### Syntax
#### Key-value pairs
- The key and value must be separated by equality sign `=`.
- The value must be wrapped within single-quotes `'`, double-quotes `"` or backticks `` ` ``.
- The key can contain letters, digits, underscore, and hyphen.
#### Ranges
- A range can be a single number, or a pair of numbers denoting the start and end values separated by double-dots `..`.
- A range must be specified in curly braces.
- Multiple ranges can be specified in a single pair of curly braces. They should be separated by comma `,`.
- Ranges can also be annotated; the annotation should be prefixed before the starting curly brace. The default annotation is `highlight`. You can customize this annotation by passing `rangeKey` value in the parser options.
- Ranges will be grouped in a single array by their annotations.
## Examples
### Example: single range
```js
import FenceParser from "@microflash/fenceparser";
const parser = new FenceParser();
console.log(parser.parse("{100}"));
```
Running the above example yields.
```js
{
highlight: [
100,
]
}
```
### Example: multiple ranges
```js
import FenceParser from "@microflash/fenceparser";
const parser = new FenceParser();
console.log(parse("{3, 7} {9..11, 101..105}"));
```
Running the above example yields.
```js
{
highlight: [
1, 3, 7, 9, 10, 11,
101, 102, 103, 104, 105,
],
}
```
### Example: ranges with custom annotations
```js
import FenceParser from "@microflash/fenceparser";
const parser = new FenceParser();
console.log(parse("{3, 7} ins{9..11, 13} del{101..105}"));
```
Running the above example yields.
```js
{
highlight: [
3, 7,
],
ins: [
9, 10, 11, 13,
],
del: [
101, 102, 103, 104, 105,
],
}
```
### Example: key-value pairs
```js
import FenceParser from "@microflash/fenceparser";
const parser = new FenceParser();
console.log(parse("data-theme='synthwave' callback=`(code) => copyToClipboard(code)`"));
```
Running the above example yields.
```js
{
'data-theme': 'synthwave',
callback: '(code) => copyToClipboard(code)',
}
```
### Example: customizing the default range's key
```js
import FenceParser from "@microflash/fenceparser";
const parser = new FenceParser({ rangeKey: "mark" });
console.log(parser.parse("{100}"));
```
Running the above example yields.
```js
{
mark: [
100,
]
}
```
Check the [fixtures](./test/fixtures/) for more examples on the syntax.
## Development
Any changes in the parser should have corresponding tests.
Run the tests with the following command.
```sh
pnpm test
```
## License
[MIT](./LICENSE.md)