初学小程序，测试switch。新建项目，然后修改app.json，添加：

    "useExtendedLib": {
      "weui": true
    },
    "usingComponents": {
      "mp-cells": "weui-miniprogram/cells/cells",
      "mp-cell": "weui-miniprogram/cell/cell",
      "mp-form": "weui-miniprogram/form/form"
    }

修改index.wxml：

<!--index.wxml-->
<mp-cell title="测试" ext-class="">
  <switch slot="footer" bindchange="bindSwitchChange" />
</mp-cell>

修改index.js：

// index.js
Page({
  data: {
    shouldTest: true
  },

  bindSwitchChange(e) {
    this.setData({ shouldTest: e.detail.value });
    console.log(shouldTest);
  }
})

然后报错：

ReferenceError: shouldTest is not defined
    at zo.bindSwitchChange (index.js? [sm]:9)
    at Object.i.safeCallback (WASubContext.js?t=wechat&s=1667317212484&v=2.27.0:1)
    at WASubContext.js?t=wechat&s=1667317212484&v=2.27.0:1
    at Cn (WASubContext.js?t=wechat&s=1667317212484&v=2.27.0:1)
    at WASubContext.js?t=wechat&s=1667317212484&v=2.27.0:1
    at oe (WASubContext.js?t=wechat&s=1667317212484&v=2.27.0:1)
    at ie (WASubContext.js?t=wechat&s=1667317212484&v=2.27.0:1)
    at WASubContext.js?t=wechat&s=1667317212484&v=2.27.0:1
    at WAServiceMainContext.js?t=wechat&s=1667317212484&v=2.27.0:1
    at o.emit (WAServiceMainContext.js?t=wechat&s=1667317212484&v=2.27.0:1)(env: macOS,mp,1.06.2209190; lib: 2.27.0)
errorReport @ WAServiceMainContext.js?t=wechat&s=1667317212484&v=2.27.0:1
thirdErrorReport @ WAServiceMainContext.js?t=wechat&s=1667317212484&v=2.27.0:1
(anonymous) @ WAServiceMainContext.js?t=wechat&s=1667317212484&v=2.27.0:1
(anonymous) @ WASubContext.js?t=wechat&s=1667317212484&v=2.27.0:1
i.safeCallback @ WASubContext.js?t=wechat&s=1667317212484&v=2.27.0:1
i.call @ WASubContext.js?t=wechat&s=1667317212484&v=2.27.0:1
message @ WASubContext.js?t=wechat&s=1667317212484&v=2.27.0:1
i.safeCallback @ WASubContext.js?t=wechat&s=1667317212484&v=2.27.0:1
(anonymous) @ WASubContext.js?t=wechat&s=1667317212484&v=2.27.0:1
Cn @ WASubContext.js?t=wechat&s=1667317212484&v=2.27.0:1
(anonymous) @ WASubContext.js?t=wechat&s=1667317212484&v=2.27.0:1
oe @ WASubContext.js?t=wechat&s=1667317212484&v=2.27.0:1
ie @ WASubContext.js?t=wechat&s=1667317212484&v=2.27.0:1
(anonymous) @ WASubContext.js?t=wechat&s=1667317212484&v=2.27.0:1
(anonymous) @ WAServiceMainContext.js?t=wechat&s=1667317212484&v=2.27.0:1
emit @ WAServiceMainContext.js?t=wechat&s=1667317212484&v=2.27.0:1
dispatch @ WAServiceMainContext.js?t=wechat&s=1667317212484&v=2.27.0:1
cb @ WAServiceMainContext.js?t=wechat&s=1667317212484&v=2.27.0:1
a @ VM146 asdebug.js:10
c @ VM146 asdebug.js:10
(anonymous) @ VM146 asdebug.js:1
f @ VM146 asdebug.js:1
g @ VM146 asdebug.js:1
(anonymous) @ VM146 asdebug.js:1
_ws.onmessage @ VM146 asdebug.js:1

请问我的问题出在哪里呢？谢谢！