Code

editor.tsx

import 'prosekit/basic/style.css'

import { createEditor } from 'prosekit/core'
import { ProseKit } from 'prosekit/react'
import { useMemo } from 'react'

import { defineExtension } from './extension'

export default function Editor() {
  const editor = useMemo(() => {
    return createEditor({ extension: defineExtension(), defaultContent })
  }, [])

  return (
    <ProseKit editor={editor}>
      <div className='box-border h-full w-full min-h-36 overflow-y-hidden overflow-x-hidden rounded-md border border-solid border-gray-200 shadow dark:border-zinc-700 flex flex-col bg-white dark:bg-neutral-900'>
        <div className='relative w-full flex-1 box-border overflow-y-scroll'>
          <div ref={editor.mount} className='ProseMirror box-border min-h-full px-[max(4rem,_calc(50%-20rem))] py-8 outline-none outline-0 [&_span[data-mention="user"]]:text-blue-500 [&_span[data-mention="tag"]]:text-violet-500 [&_pre]:text-white [&_pre]:bg-zinc-800'></div>
        </div>
      </div>
    </ProseKit>
  )
}

const defaultContent = `
  <p>Here is a link that changes color every second: <a href="https://www.example.com">example link</a>
`

extension.ts

import { defineBasicExtension } from 'prosekit/basic'
import { union } from 'prosekit/core'
import { defineReactMarkView } from 'prosekit/react'

import LinkView from './link-view'

export function defineExtension() {
  return union(
    defineBasicExtension(),
    defineReactMarkView({
      name: 'link',
      component: LinkView,
    }),
  )
}

export type EditorExtension = ReturnType<typeof defineExtension>

link-view.tsx

import type { ReactMarkViewProps } from 'prosekit/react'
import {
  useEffect,
  useState,
} from 'react'

const colors = [
  '#f06292',
  '#ba68c8',
  '#9575cd',
  '#7986cb',
  '#64b5f6',
  '#4fc3f7',
  '#4dd0e1',
  '#4db6ac',
  '#81c784',
  '#aed581',
  '#ffb74d',
  '#ffa726',
  '#ff8a65',
  '#d4e157',
  '#ffd54f',
  '#ffecb3',
]

function pickRandomColor() {
  return colors[Math.floor(Math.random() * colors.length)]
}

export default function Link(props: ReactMarkViewProps) {
  const [color, setColor] = useState(colors[0])
  const { mark, contentRef } = props
  const href = mark.attrs.href as string

  useEffect(() => {
    const interval = setInterval(() => {
      setColor(pickRandomColor())
    }, 1000)
    return () => clearInterval(interval)
  }, [])

  return (
    <a
      href={href}
      ref={contentRef}
      style={{ color, transition: 'color 1s ease-in-out' }}
    >
    </a>
  )
}