js计算base64文件流大小

getImgSize(str) {
    //获取base64图片大小，返回KB数字
    var str = base64url.replace('data:image/jpeg;base64,', '');//这里根据自己上传图片的格式进行相应修改

    var strLength = str.length;
    var fileLength = parseInt(strLength - (strLength / 8) * 2);

    // 由字节转换为KB
    var size = "";
    size = (fileLength / 1024).toFixed(2);

    return parseInt(size);

  },

base64:

data:image/jpeg;base64,/9j/4AAQSkZJRgABAQAASABIAAD/4QBYRXhpZxxxxxxxkopKACiiigApaSloA/9k=