litemall/litemall-wx/lib/vant-weapp/mixins/observer/behavior.js

export const behavior = Behavior({
    methods: {
        set(data, callback) {
            return new Promise(resolve => {
                this.setData(data, () => {
                    if (callback && typeof callback === 'function') {
                        callback.call(this);
                    }
                    resolve();
                });
            });
        }
    }
});