如何运行此项目

1. 需要一个有绑定小程序开发者的微信号，因为weui拓展库引入的方式需要用到真实的appid
2. 需要用到npm安装一部分额外的包，然后在微信开发者工具中进行工具->构建npm操作，才能确保额外组件的正常引入

Tips

1. 第四章中对vtabs的源码进行了部分修改，如下

// index.js
const windowHeight = wx.getSystemInfoAsync().windowHeight
calcChildHeight: function(target) {
        var _this = this;

        target.calcHeight(function(rect) {
            _this.data._contentHeight[target.data.tabIndex] = rect.height;
            if (_this._calcHeightTimer) {
                clearTimeout(_this._calcHeightTimer);
            }
            _this._calcHeightTimer = setTimeout(function() {
                _this.calcHeight();
            }, 100);
        });
    },
handleContentScroll: function handleContentScroll(e) {
        var _heightRecords = this.data._heightRecords;
        if (_heightRecords.length === 0) return;
        var length = this.data.vtabs.length;
        var scrollTop = e.detail.scrollTop;
        var index = -1;
        // 增加窗口高度
        if (scrollTop >= _heightRecords[this.data.activeTab] - windowHeight - 150) {
            this.triggerEvent('scrolltoindexlower', {
                index: this.data.activeTab
            });
        }
        if (scrollTop >= _heightRecords[0] - windowHeight) {
            for (var i = 1; i < length; i++) {
                if (scrollTop >= _heightRecords[i - 1] - windowHeight && scrollTop < _heightRecords[i] - windowHeight) {
                    index = i;
                    break;
                }
            }
        } else {
            index = 0
        }
        if (index > -1 && index !== this.data.activeTab) {
            this.triggerEvent('change', {
                index: index
            });
            this.setData({
                activeTab: index
            });
        }
    }