javascript - 无法返回适当的值

Question

<分区>

Answer 1

如果是异步的，使用回调:

getCams(function(media_list) {
    // do stuff with media_list
});    

function getCams(callback){
  var media_list = [];
  MediaStreamTrack.getSources(function(sourceInfos){
    var i=0;
    while(i!=sourceInfos.length){
      if (sourceInfos[i].kind == 'video'){
        var temp = [];
        temp.push(sourceInfos[i].id);
        temp.push(sourceInfos[i].label);
        media_list.push(temp);
      }
      i++;
    }
    console.log(media_list);
    callback(media_list);
  });
}