我已经序列化了Canvas对象，它是我通过canvas.toJSON()获得的，在反序列化canvas.loadFromJSON(jsonObj, canvas.renderAll.bind(canvas))之后，我不能在Canvas中操作对象，它们是不可 Select 的.
Expecting behavior:个 反序列化之后，所有对象都必须像序列化之前一样是可 Select 和可管理的.
我在codesandbox年内复制了一期
How to reproduce:个
也许我做错了什么？将乐于提供任何帮助和建议.
经过一番研究，我发现了问题出在哪里.
Why I couldn't manipulate deserialized object?
Because there were 2 canvas html elements. As we can see from screenshot, there are 2 canvases. First one (green border) with image and the second (red border) is empty. And all my interaction was with empty (red) canvas. If I delete second canvas I can interact with image object.
useEffect的StrictMode个回调中有Why did it happen?个调用两次，这就是为什么我得到嵌套的画布html元素的原因.
How to fix it?有几种变通方法可以摆脱它.
StrictMode.显而易见，简单，但不想要的解决方案.let wasCalled = false;
export default function App() {
// ...
useEffect(() => {
if (wasCalled) {
return;
}
wasCalled = true;
// ...
},[])
也许还有更好的解决方案，比如以其他方式初始化画布实例，但目前对我来说还可以.