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| <!DOCTYPE html> | |
| <html lang="en"> | |
| <head> | |
| <meta charset="UTF-8" /> | |
| <meta name="viewport" content="width=device-width, initial-scale=1.0" /> | |
| <title>Intro to XState</title> | |
| <link rel="stylesheet" href="styles.css" /> | |
| </head> | |
| <body> | |
| <div id="box"></div> | |
| <script src="https://unpkg.com/[email protected]/dist/xstate.js"></script> | |
| <script src="index.js"></script> | |
| </body> | |
| </html> |
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| const { createMachine, interpret, assign } = XState; | |
| const dragDropMachine = createMachine({ | |
| initial: 'idle', | |
| context: { | |
| // the position of the box | |
| x: 0, | |
| y: 0, | |
| // where you clicked | |
| pointerx: 0, | |
| pointery: 0, | |
| // how far from where you clicked | |
| dx: 0, // how far: x | |
| dy: 0, // how far: y | |
| }, | |
| states: { | |
| idle: { | |
| on: { | |
| // event: nextstate | |
| mousedown: { | |
| target: 'dragging', | |
| actions: assign((context, mouseEvent) => { | |
| return { | |
| ...context, | |
| pointerx: mouseEvent.clientX, | |
| pointery: mouseEvent.clientY | |
| } | |
| }) | |
| } | |
| } | |
| }, | |
| dragging: { | |
| on: { | |
| mousemove: { | |
| target: 'dragging', | |
| actions: assign((context, mouseEvent) => { | |
| return { | |
| ...context, | |
| dx: mouseEvent.clientX - context.pointerx, | |
| dy: mouseEvent.clientY - context.pointery | |
| } | |
| }) | |
| }, | |
| mouseup: { | |
| target: 'idle', | |
| actions: assign((context) => { | |
| return { | |
| ...context, | |
| x: context.x + context.dx, | |
| y: context.y + context.dy, | |
| dx: 0, | |
| dy: 0 | |
| } | |
| }) | |
| // change context.x and context.y | |
| } | |
| } | |
| } | |
| } | |
| }) | |
| const body = document.body; | |
| const box = document.getElementById('box') | |
| const dragDropService = interpret(dragDropMachine) | |
| .onTransition(state => { | |
| if (state.changed) { | |
| console.log(state.context) | |
| box.style.setProperty('left', | |
| // where the box is + how far the box moved | |
| state.context.x + state.context.dx + 'px') | |
| box.style.setProperty('top', | |
| state.context.y + state.context.dy + 'px') | |
| body.dataset.state = state.toStrings().join(' ') | |
| } | |
| }) | |
| .start(); | |
| body.addEventListener('mousedown', event => { | |
| // event.clientX | |
| // event.clientY | |
| dragDropService.send(event) | |
| }) | |
| body.addEventListener('mouseup', event => { | |
| dragDropService.send(event) | |
| }) | |
| body.addEventListener('mousemove', event => { | |
| dragDropService.send(event) | |
| }) | |
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a simpler version (less math :) and more logic in the state machine) that also works if the box doesn't start at position 0,0: https://gist.github.com/bwaidelich/aa5f33c4937e070dd3c53c6345623167