React - canvas draw.js

import React, { Component } from 'react';

export default class CanvasRing extends Component {

  constructor(props) {
    super(props);
  }

  initrender(){
    const canvas = ReactDOM.findDOMNode(this.refs.canvas_ring);
    var ctx = canvas.getContext("2d");
    ctx.beginPath();
    ctx.arc((this.props.ring_width)/2,(this.props.ring_width)/2,(this.props.ring_width-10)/2,0,2*Math.PI);
    ctx.strokeStyle = "#bcbce4";
    ctx.fillStyle = "red";
    ctx.lineWidth = 10;
    ctx.stroke();
  }

  componentDidMount() {
    this.initrender();
  }
  
  componentDidUpdate(){
    this.initrender();
  }

  render() {
    return (
      <spui-div class="cenvas_content">
        <canvas ref="canvas_ring" id="canvas_ring" width={this.props.ring_width} height={this.props.ring_width}></canvas>
      </spui-div>
    );
  }
}