wx.request中，url传递的参数中有变量怎么写

var val = 666;
wx.request({
                 url: 'https://domainname/url?id='+ val,
});

例子：上传图片案例

// 上传图片
  chooseImage: function () {
    var that = this;
    // 选择图片
    var openid = wx.getStorageSync('openid');
    wx.chooseImage({
      count: 1, // 默认9
      sizeType: ['original', 'compressed'], // 可以指定是原图还是压缩图，默认二者都有
      sourceType: ['album', 'camera'], // 可以指定来源是相册还是相机，默认二者都有
      success: function (res) {
        console.log('获取的ID' + openid);
        var tempFilePaths = res.tempFilePaths   // 返回选定照片的本地文件路径列表，tempFilePath可以作为img标签的src属性显示图片
        wx.uploadFile({
          url: app.config.apiBase + '?type={type}&openid=' + openid,
          // url: app.config.apiBase + '?type={type}&openid={openid}',
          filePath: tempFilePaths[0],
          name: 'file',
          formData: {
            user: 'test'
          },
          success(res) {
            console.log(res);
            const data = http://www.wxapp-union.com/res.data
          }
        })
        that.setData({
          item: tempFilePaths[0],
          imgBoolean: false
        });
      }
    })
  },
  // 图片预览
  previewImage: function (e) {
    var current = e.target.dataset.src
    wx.previewImage({
      current: current,
      urls: [current]
    })
    // console.log("这是1" + current);
  },
  //删除图片
  deleteImg: function (e) {
    var that = this;
    var images = that.data.uploadedImages;
    that.setData({
      uploadedImages: images,
      imgBoolean: true
    });
  }, 

  <view class="item">
      <!-- 添加按钮 -->
      <view class="addIcon" bindtap="chooseImage" wx:if="{{imgBoolean}}">
        <view class='addBtn'>+</view>
      </view>
      <!-- 上传的图 -->
      <view class='itemImg'>
        <image src="http://www.wxapp-union.com/{{item}}" data-src="http://www.wxapp-union.com/{{item}}" bindtap="previewImage" mode="aspectFill" />
        <!-- 删除按钮 -->
        <view class="delete" bindtap="deleteImg" data-index="{{index}}">X</view>
      </view>
    </view>