list: [{

        id: 1,

        name: '张三',

        cars: [{

            id: 1,

            name: '奔驰'

          },

          ......

        ]

      },

      ......]

// index.wxml
<view class="container">

  <view wx:for="{{list}}" wx:key="id" class="list">

    <view>姓名：{{item.name}}</view>

    <wxs module="m">

      var getCarCount = function(array) {

        var count = 0;

        for (var i = 0; i < array.length; ++i) {

          count++;

        }

        return count;

      }

      module.exports.getCarCount = getCarCount;

    </wxs>

    <view class="gray-color">拥有{{m.getCarCount(item.cars)}}辆车</view>

  </view>

</view>

// index.js的list数据如下

data: {

    list: [{

        id: 1,

        name: '张三',

        cars: [{

            id: 1,

            name: '奔驰'

          },

          {

            id: 2,

            name: '宝马'

          }

        ]

      },

      {

        id: 2,

        name: '李四',

        cars: [{

            id: 3,

            name: '卡迪拉克'

          },

          {

            id: 4,

            name: '英菲尼迪'

          },

          {

            id: 5,

            name: '马自达'

          }

        ]

      },

      {

        id: 3,

        name: '王五',

        cars: [{

          id: 6,

          name: '飞度'

        }]

      }

    ]

  },