说明： 三级联动，微信小程序实例。
做页面开发或客户端程序开发，都会碰到几个下拉菜单联动的情况，比如常见的省，市，区三级联动。
这种下拉菜单该怎样联动？下面一起来看下，以页面开发为例子。
(Three-level linkage, Wechat applet example)
文件列表：
littleAPP-master\app.js, 669 , 2018-07-05
littleAPP-master\app.json, 254 , 2018-07-05
littleAPP-master\app.wxss, 194 , 2018-07-05
littleAPP-master\model\model.js, 3570 , 2018-07-05
littleAPP-master\model\model.wxml, 1415 , 2018-07-05
littleAPP-master\model\model.wxss, 1473 , 2018-07-05
littleAPP-master\pages\index\index.js, 4565 , 2018-07-05
littleAPP-master\pages\index\index.json, 46 , 2018-07-05
littleAPP-master\pages\index\index.wxml, 1413 , 2018-07-05
littleAPP-master\pages\index\index.wxss, 1385 , 2018-07-05
littleAPP-master\pages\modelTest\modelTest.js, 900 , 2018-07-05
littleAPP-master\pages\modelTest\modelTest.json, 48 , 2018-07-05
littleAPP-master\pages\modelTest\modelTest.wxml, 244 , 2018-07-05
littleAPP-master\pages\modelTest\modelTest.wxss, 55 , 2018-07-05
littleAPP-master\project.config.json, 638 , 2018-09-28
littleAPP-master\README.md, 462 , 2018-07-05
littleAPP-master\utils\area.js, 495003 , 2018-07-05
littleAPP-master\utils\util.js, 460 , 2018-07-05
littleAPP-master\pages\index, 0 , 2018-07-05
littleAPP-master\pages\modelTest, 0 , 2018-07-05
littleAPP-master\chooseArea, 0 , 2018-07-05
littleAPP-master\model, 0 , 2018-07-05
littleAPP-master\pages, 0 , 2018-07-05
littleAPP-master\utils, 0 , 2018-07-05
littleAPP-master, 0 , 2018-09-28
好评：
