完整错误日志:
不变违规:对象作为React子对象无效(找到:[object HTMLCanvasElement])。如果您要渲染子集合,请使用数组。在CanvasEngine中
上面的错误发生在组件中:在CanvasEngine中
渲染没有返回。 elementCanvas有什么问题:HTMLCanvasElement ?!
我希望从代码中获取html元素,我尝试将其存储在this.state中,但仍然无法正常工作...
import * as React from "react";
export class CanvasEngine extends React.Component<{name:string}, {}, void > {
private elementCanvas: HTMLCanvasElement;
private programName: string = " test ";
private width: number = 100;
private height: number = 100;
private test: number = 1;
constructor(props: {name:string}) {
super(props);
this.state = { elementCanvas : document.createElement('canvas') };
//super( {name} );
this.elementCanvas = document.createElement('canvas');
this.elementCanvas.width = 200;
this.elementCanvas.height = 200;
//document.body.appendChild(this.elementCanvas);
console.log("constructor");
this.tick();
}
componentDidMount() {
console.log("!componentDidMount!");
}
tick() {
let context = this.elementCanvas.getContext("2d");
context.fillStyle = "lime";
context.clearRect(0, 0, this.width, this.height);
context.save();
context.translate(100, 100);
this.test += 0.01;
context.rotate(this.test);
context.fillStyle = "#F00";
context.fillRect(50, 50, 100, 100);
context.restore();
setTimeout( () => { this.tick() } , 30 );
}
public render() {
return <> {this.elementCanvas} </>;
}
}
//
import * as React from "react";
import * as ReactDOM from "react-dom";
import { ProjectName } from "./components/project-name";
import { CanvasEngine } from "./components/canvas";
ReactDOM.render(
<>
<h1>Page title</h1>,
<CanvasEngine name="nidza" />,
<ProjectName compiler="TypeScript" framework="React" />
</>,
document.getElementById("root")
);
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.0.1/react.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.0.1/react-dom.min.js"></script>
而不是使用document.createElement()
,你可以尝试使用React.createElement()
。