Youtube UploadWidget上的onUploadStart？

当我们使用YouTube UploadWidget添加视频时，在上传过程中会有一个加载器。但是当我们添加一个视频文件时，什么也没有发生！所以用户不知道他的文件正在上传

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是否有类似“onUploadStart”这样的事件来自己制作加载程序？

我使用此代码检查上传过程何时结束并开始视频处理

var stack = [];

function onStateChange(event) {
    var state = event.data.state;
    switch (state) {
        case YT.UploadWidgetState.RECORDING:
            break;
        case YT.UploadWidgetState.PENDING:
            break;
        case YT.UploadWidgetState.STOPPED:
            if(stack.pop() == "US")
            {
              //video is uploaded and processing has been started, I show loader here
                stack.push("US");
            }
            stack.push("S");
            break;
    }
}

function onUploadSuccess(event) {
    stack.push("US");
}

function onProcessingComplete(event) {
    if(stack.pop() == "S" && stack.pop() == "US")
    {
        stack = [];
    }
//disable spinner
}

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我使用此代码检查上传过程何时结束并开始视频处理

var stack = [];

function onStateChange(event) {
    var state = event.data.state;
    switch (state) {
        case YT.UploadWidgetState.RECORDING:
            break;
        case YT.UploadWidgetState.PENDING:
            break;
        case YT.UploadWidgetState.STOPPED:
            if(stack.pop() == "US")
            {
              //video is uploaded and processing has been started, I show loader here
                stack.push("US");
            }
            stack.push("S");
            break;
    }
}

function onUploadSuccess(event) {
    stack.push("US");
}

function onProcessingComplete(event) {
    if(stack.pop() == "S" && stack.pop() == "US")
    {
        stack = [];
    }
//disable spinner
}