删除视频url, 需要触发onchange事件

[chengxintuan]

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())
})

}