我在index.wxml 里定义了一个组件<web-view id="myWebView" bindmessage="onMessage"  src="{{exh5url}}" ></web-view>然后在index.js里的onReady去获取上下文为空onReady: function () {

    const webViewContext = this.selectComponent('#myWebView');

      console.log(webViewContext);

      if (webViewContext) {

        webViewContext.postMessage({ data: 'Hello from Mini Program' });

      } else {

        console.error('Failed to get webViewContext');

      }

},