mdast-excerpt
v0.0.10
Published
Build an excerpt from a markdown AST
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mdast-excerpt
mdast-excerpt
allows you to get an excerpt from a markdown post. The code is
"borrowed" from gatsby-transformer-remark
, which makes it possible to use excerpt
generation in other contexts outside of GatsbyJS. If you
want to know how the result looks like, check
Using Excerpts at GatsbyJS.
Input is a full markdown AST, output a pruned AST with the desired excerpt length and intact markup.
This plugin becomes useful if the excerpt would stop in the middle of marked up text:
This is a **bold text**
-> This is a **bold te...
when truncated by string length. With mdast-excerpt
, then markup is truncated
correctly:
This is a **bold text**
-> This is a bold te...
My personal favourite is using mdast-excerpt
in combination with
react-markdown (see futher below for
usage).
Install
npm install mdast-excerpt
Use
const remark = require("remark")
const html = require("remark-html")
const excerptAst = require("mdast-excerpt")
// fake the plugin
const asExcerpt = options => node => excerptAst(node, options || {})
const input = "abc abc **def ghi**"
remark()
.use(asExcerpt, { omission: " Read More", pruneLength: 14 })
.use(html)
.processSync(input)
Usage with react-markdown
You can use the astPlugins
prop to supply the excerptAst
transformer:
import React from "react"
import ReactDOM from "react-dom"
import ReactMarkdown from "react-markdown"
import excerptAst from "mdast-excerpt"
const MarkdownExcerpt = ({ source, pruneLength = 14 }) => (
<ReactMarkdown
source={source}
astPlugins={[ast => excerptAst(ast, { pruneLength })]}
/>
)
const App = () => {
const input = "abc abc **def ghi**"
return <MarkdownExcerpt source={input} pruneLength={13} />
}
React.ReactDOM.render(<App />, document.getElementById("root"))
API
You can call excerptAst
as follows:
excerptAst(tree, { pruneLength: 1, truncate: false, omission:
…})
The options are
pruneLength
: max length of the excerpt (default 140)truncate
: truncate on exact length (true) or stop at whole words (default false)excerptSeparator
: supply an excerpt separator that is used to detect the excerpt. A common choice would be<!-- end -->
. If the separator is not found,excerptAst
falls back topruneLength
(default undefined).omission
: the omission text to add after the excerpt (default…
)
Contributors
- Dillon Parfitt (DParfitt)