setTimeout了也是duration还是0，奇怪的是另外一个小程序同样的代码，同样的环境是可以获取到的

var src ='share/static/voice/openauto.wav'

var innerAudioContext = wx.createInnerAudioContext()

innerAudioContext.autoplay = true

innerAudioContext.src = src

console.log(innerAudioContext.duration)；

innerAudioContext.onPlay(() => {

 console.log('onPlay:开始播放');

});

innerAudioContext.onError((res) => {

 console.log("onError:" + res.errMsg);

});

innerAudioContext.onCanplay(()=> {

  innerAudioContext.duration;

  setTimeout(() => {console.log(innerAudioContext.duration);}, 3000)

});