I'm writing a markdown text editor using slate.js. I'm trying to implement the following live-rendering effect (from Typora):
As you can see,
- When I'm typing, the text is turning to bold automatically.
- When I hit the space key, the four asterisks disappeared, only the text itself is visible.
- When I focus the cursor back to the text, the asterisks shows up again (so I can modify them).
I've already implemented the first item thanks to the example of MarkdownPreview, here is the code of it (take from the slate repository):
import Prism from 'prismjs'
import React, { useCallback, useMemo } from 'react'
import { Slate, Editable, withReact } from 'slate-react'
import { Text, createEditor, Descendant } from 'slate'
import { withHistory } from 'slate-history'
import { css } from '@emotion/css'
// eslint-disable-next-line
;Prism.languages.markdown=Prism.languages.extend("markup",{}),Prism.languages.insertBefore("markdown","prolog",{blockquote:{pattern:/^>(?:[\t ]*>)*/m,alias:"punctuation"},code:[{pattern:/^(?: {4}|\t).+/m,alias:"keyword"},{pattern:/``.+?``|`[^`\n]+`/,alias:"keyword"}],title:[{pattern:/\w+.*(?:\r?\n|\r)(?:==+|--+)/,alias:"important",inside:{punctuation:/==+$|--+$/}},{pattern:/(^\s*)#+.+/m,lookbehind:!0,alias:"important",inside:{punctuation:/^#+|#+$/}}],hr:{pattern:/(^\s*)([*-])([\t ]*\2){2,}(?=\s*$)/m,lookbehind:!0,alias:"punctuation"},list:{pattern:/(^\s*)(?:[*+-]|\d+\.)(?=[\t ].)/m,lookbehind:!0,alias:"punctuation"},"url-reference":{pattern:/!?\[[^\]]+\]:[\t ]+(?:\S+|<(?:\\.|[^>\\])+>)(?:[\t ]+(?:"(?:\\.|[^"\\])*"|'(?:\\.|[^'\\])*'|\((?:\\.|[^)\\])*\)))?/,inside:{variable:{pattern:/^(!?\[)[^\]]+/,lookbehind:!0},string:/(?:"(?:\\.|[^"\\])*"|'(?:\\.|[^'\\])*'|\((?:\\.|[^)\\])*\))$/,punctuation:/^[\[\]!:]|[<>]/},alias:"url"},bold:{pattern:/(^|[^\\])(\*\*|__)(?:(?:\r?\n|\r)(?!\r?\n|\r)|.)+?\2/,lookbehind:!0,inside:{punctuation:/^\*\*|^__|\*\*$|__$/}},italic:{pattern:/(^|[^\\])([*_])(?:(?:\r?\n|\r)(?!\r?\n|\r)|.)+?\2/,lookbehind:!0,inside:{punctuation:/^[*_]|[*_]$/}},url:{pattern:/!?\[[^\]]+\](?:\([^\s)]+(?:[\t ]+"(?:\\.|[^"\\])*")?\)| ?\[[^\]\n]*\])/,inside:{variable:{pattern:/(!?\[)[^\]]+(?=\]$)/,lookbehind:!0},string:{pattern:/"(?:\\.|[^"\\])*"(?=\)$)/}}}}),Prism.languages.markdown.bold.inside.url=Prism.util.clone(Prism.languages.markdown.url),Prism.languages.markdown.italic.inside.url=Prism.util.clone(Prism.languages.markdown.url),Prism.languages.markdown.bold.inside.italic=Prism.util.clone(Prism.languages.markdown.italic),Prism.languages.markdown.italic.inside.bold=Prism.util.clone(Prism.languages.markdown.bold); // prettier-ignore
const MarkdownPreviewExample = () => {
const renderLeaf = useCallback(props => <Leaf {...props} />, [])
const editor = useMemo(() => withHistory(withReact(createEditor())), [])
const decorate = useCallback(([node, path]) => {
const ranges = []
if (!Text.isText(node)) {
return ranges
}
const getLength = token => {
if (typeof token === 'string') {
return token.length
} else if (typeof token.content === 'string') {
return token.content.length
} else {
return token.content.reduce((l, t) => l + getLength(t), 0)
}
}
const tokens = Prism.tokenize(node.text, Prism.languages.markdown)
let start = 0
for (const token of tokens) {
const length = getLength(token)
const end = start + length
if (typeof token !== 'string') {
ranges.push({
[token.type]: true,
anchor: { path, offset: start },
focus: { path, offset: end },
})
}
start = end
}
return ranges
}, [])
return (
<Slate editor={editor} value={initialValue}>
<Editable
decorate={decorate}
renderLeaf={renderLeaf}
placeholder="Write some markdown..."
/>
</Slate>
)
}
const Leaf = ({ attributes, children, leaf }) => {
return (
<span
{...attributes}
className={css`
font-weight: ${leaf.bold && 'bold'};
font-style: ${leaf.italic && 'italic'};
text-decoration: ${leaf.underlined && 'underline'};
${leaf.title &&
css`
display: inline-block;
font-weight: bold;
font-size: 20px;
margin: 20px 0 10px 0;
`}
${leaf.list &&
css`
padding-left: 10px;
font-size: 20px;
line-height: 10px;
`}
${leaf.hr &&
css`
display: block;
text-align: center;
border-bottom: 2px solid #ddd;
`}
${leaf.blockquote &&
css`
display: inline-block;
border-left: 2px solid #ddd;
padding-left: 10px;
color: #aaa;
font-style: italic;
`}
${leaf.code &&
css`
font-family: monospace;
background-color: #eee;
padding: 3px;
`}
`}
>
{children}
</span>
)
}
const initialValue: Descendant[] = [
{
type: 'paragraph',
children: [
{
text:
'Slate is flexible enough to add **decorations** that can format text based on its content. For example, this editor has **Markdown** preview decorations on it, to make it _dead_ simple to make an editor with built-in Markdown previewing.',
},
],
},
{
type: 'paragraph',
children: [{ text: '## Try it out!' }],
},
{
type: 'paragraph',
children: [{ text: 'Try it out for yourself!' }],
},
]
export default MarkdownPreviewExample
My question is, how can I implement the second and third items? I've been thinking about it for a long time, but didn't find any good way to achieve them.
