监听父元素宽高，自适应插件大小

参考文档：ResizeObserver

通常用于第三方插件宽高适应：echarts/antv等

//监听对象变化回调
const resizeObserver = new ResizeObserver(entries => {
    
  for (let entry of entries) {
    
    if(entry.contentBoxSize) {
    
      const width = document.getElementById('fatherbox').clientWidth
      const height = document.getElementById('fatherbox').clientHeight
      document.getElementById('sonbox').style.width = width
    } 
  }
});
//初始化注册监听对象
const init = () => {
    
  resizeObserver.observe(document.getElementById('fatherbox'));
}