Small program development, taBar can not achieve the function

< br / > the following is the app. The json code in the < br / > {< br / >" 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": [{< br / > "pagePath" : "pages/index/index", < br / > "text", "home page", < br / > "iconPath" : "icons/_home.png",
"selectedIconPath": "icons/home.png"
},
{
"pagePath": "pages/category/index",
"text": "category ",
"iconPath": "icons/_category.png",
"selectedIconPath": "icons/category.png"
},
{
"pagePath": "pages/cart/index",
"text": "shopping cart ",
"iconPath": "icons/_cart.png",
"selectedIconPath": "icons/cart.png"
},
{
"pagePath": "pages/my/index",
"text": "My ",
"iconPath": "icons/_my.png",
"selectedIconPath": "icons/my.png"
}]
},
"style": "v2",
"sitemapLocation": "sitemap.json"
}