with-drag.html

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <div id="root"></div>

    <script src="https://unpkg.com/@babel/standalone/babel.js"></script>
    <script type="importmap">
        {
            "imports": {
                "react": "https://esm.sh/react?dev",
                "react-dom/client": "https://esm.sh/react-dom/client?dev"
            }
        }
    </script>

    <script type="text/babel" data-type="module">
        import React, { StrictMode, useState, useRef, useEffect, useMemo } from 'react'

        import { createRoot } from 'react-dom/client'

        function DragMe({ children }) {
            const ref = useRef()

            useEffect(() => {
                const { current: container } = ref
                container.state = {}

                container.onmousedown = handleMouseDown
                container.onmouseup = handleMouseUp
                container.onmousemove = handleMouseMove
            }, [])

            const handleMouseDown = event => {
                const { current: container } = ref
                const { state } = container

                if (!state.dragging) {
                    state.dragging = true

                    const { clientX: px, clientY: py } = event

                    state.pix = px
                    state.piy = py

                    const { x, y, width, height } = container.getBoundingClientRect()

                    state.cix = x
                    state.ciy = y
                }
            }

            const handleMouseUp = () => {
                const { current: container } = ref
                const { state } = container

                if (state.dragging) {
                    state.dragging = false
                }
            }

            const handleMouseMove = event => {
                const { current: container } = ref
                const { state } = container

                if (state.dragging) {
                    const { clientX: px, clientY: py } = event
                    const { cix, ciy, pix, piy } = state
                    const { current: container } = ref
                    const { x, y, width, height } = container.getBoundingClientRect()

                    const tx = cix + px - pix
                    const ty = ciy + py - piy

                    container.style.left = `${tx}px`
                    container.style.top = `${ty}px`
                }
            }

            return <div ref={ref} style={{ position: 'absolute', cursor: 'pointer' }}>{children}</div>
        }

        function withDrag(component) {
            return <DragMe>{component}</DragMe>
        }

        function App() {
            return <>
                <DragMe><h1>Pryvit, Mir!</h1></DragMe>
                {withDrag(<h1>Hello, World!</h1>)}
                {withDrag(<h1>Ciao, Mondo!</h1>)}
            </>
        }

        const root = createRoot(document.getElementById('root'))
        root.render(<StrictMode><App /></StrictMode>)
    </script>
</body>

</html>