uni.webView 有没有文档

uni.webView 这个有没有文档，
这个方法只在https://uniapp.dcloud.io/api/router?id=event-channel 提了一句话
在uniapp引入uni的H5页面 uni.webView 显示undefined
methods: {
back() {
console.log(uni.webView);
uni.webView.navigateBack();
}
}

undefined at webpack-internal:///./node_modules/babel-loader/lib/index.js!./node_modules/@dcloudio/vue-cli-plugin-uni/packages/webpack-preprocess-loader/index.js?!./node_modules/@dcloudio/vue-cli-plugin-uni/packages/webpack-preprocess-loader/index.js?!./node_modules/@dcloudio/vue-cli-plugin-uni/packages/webpack-uni-app-loader/using-components.js!./node_modules/@dcloudio/vue-cli-plugin-uni/packages/vue-loader/lib/index.js?!./node_modules/@dcloudio/vue-cli-plugin-uni/packages/webpack-scoped-loader/index.js!../../../pages/index/zhubotixianlogin.vue?vue&type=script&lang=js&:39
11:35:26.799 [Vue warn]: Error in v-on handler: "TypeError: Cannot read property 'navigateBack' of undefined"
11:35:26.840 found in
11:35:26.881 ---> at pages/index/zhubotixianlogin.vue at http://192.168.0.108:8081/static/js/chunk-vendors.js:3883
11:35:26.902 [system] TypeError: Cannot read property 'navigateBack' of undefined at http://192.168.0.108:8081/static/js/chunk-vendors.js:124