删除视频url, 需要触发onchange事件

>
removeSource = index => {
    let sourcesCopy = this.state.sources.concat([])
    sourcesCopy.splice(index, 1)
    this.setState({sources: sourcesCopy},() => {
     // 删除url链接的时候应该也要同步更新html

      this.props.onChange && this.props.onChange(this.generateHtml())
    })
  }