layer提示框添加多个按钮选择的实例

function jumpChoose(argu) { //询问框 var index = layer.confirm('下载文件还是在线预览呢？', {  btn: ['在线预览','下载',"关闭"], //按钮  shade: false //不显示遮罩 }, function(){  //关闭提示框  layer.close(index); }, function(){  //关闭提示框  layer.close(index); }, function(){  //关闭提示框  layer.close(index); });}