小程序开发，taBar无法实现功能

在微信开发平台里面中使用taBar实现底层菜单渲染，但是鼠标点击图标发现图标无法切换，求解

如下是app.json中的代码
{
"pages": [
"pages/index/index",
"pages/category/index",
"pages/cart/index",
"pages/my/index"
],
"window": {
"backgroundTextStyle": "light",
"navigationBarBackgroundColor": "#fff",
"navigationBarTitleText": "Weixin",
"navigationBarTextStyle": "black"
},
"tabBar": {
"color": "#999",
"selectedColor": "#FF5700",
"backgroundColor": "#fafafa",
"list": [{
"pagePath": "pages/index/index",
"text": "首页",
"iconPath": "icons/_home.png",
"selectedIconPath": "icons/home.png"
},
{
"pagePath": "pages/category/index",
"text": "分类",
"iconPath": "icons/_category.png",
"selectedIconPath": "icons/category.png"
},
{
"pagePath": "pages/cart/index",
"text": "购物车",
"iconPath": "icons/_cart.png",
"selectedIconPath": "icons/cart.png"
},
{
"pagePath": "pages/my/index",
"text": "我的",
"iconPath": "icons/_my.png",
"selectedIconPath": "icons/my.png"
}]
},
"style": "v2",
"sitemapLocation": "sitemap.json"
}

看看console肯定是报错了，解决报错就好了