Javascript 未捕获类型错误：无法读取属性'；查询选择器'；空的_Javascript_Visual Studio_Cordova

Javascript 未捕获类型错误：无法读取属性'；查询选择器'；空的

javascript visual-studio cordova

Javascript 未捕获类型错误：无法读取属性'；查询选择器'；空的,javascript,visual-studio,cordova,Javascript,Visual Studio,Cordova,我正在Visual Studio 2015中使用Cordova应用程序。我添加了一个简单的按钮，可以将应用程序的背景颜色更改为红色。但它给出了上述错误 index.html <!DOCTYPE html> <html> <head> <!-- Customize the content security policy in the meta tag below as needed. Add 'unsafe-inline'

我正在Visual Studio 2015中使用Cordova应用程序。我添加了一个简单的按钮，可以将应用程序的背景颜色更改为红色。但它给出了上述错误

index.html

<!DOCTYPE html>
<html>
    <head>
    <!--
        Customize the content security policy in the meta tag below as needed. Add 'unsafe-inline' to default-src to enable inline JavaScript.
        For details, see http://go.microsoft.com/fwlink/?LinkID=617521
    -->
        <meta http-equiv="Content-Security-Policy" content="default-src 'self' data: gap: https://ssl.gstatic.com 'unsafe-eval'; style-src 'self' 'unsafe-inline'; media-src *">

        <meta name="format-detection" content="telephone=no">
        <meta name="msapplication-tap-highlight" content="no">
        <meta name="viewport" content="user-scalable=no, initial-scale=1, maximum-scale=1, minimum-scale=1, width=device-width">
        <link rel="stylesheet" type="text/css" href="css/index.css">
        <title>WeatherApp</title>
    </head>
    <body>
        <p>Hello World</p>
        <input type="button" name="color" value="Change Color" id="color" onclick="changeColor()">
        <script type="text/javascript" src="cordova.js"></script>
        <script type="text/javascript" src="scripts/platformOverrides.js"></script>
        <script type="text/javascript" src="scripts/index.js"></script>
    </body>
</html>

}）（）

您没有ID为

devicerady

的div，因此您的

parentElement

将为空

编辑：我认为您可以删除整个块，因为它属于创建新项目时的默认cordova页面布局：

// TODO: Cordova has been loaded. Perform any initialization that requires Cordova here.
var parentElement = document.getElementById('deviceready');
var listeningElement = parentElement.querySelector('.listening');
var receivedElement = parentElement.querySelector('.received');
listeningElement.setAttribute('style', 'display:none;');
receivedElement.setAttribute('style', 'display:block;');

我认为dom尚未加载，您尝试进行选择，以便它返回空值。尝试将这些线移到OnDevicerady（）之外

我认为这不是DOM加载顺序的问题。看起来更像是从默认Cordova HTML索引页面中删除的搜索div，无需编辑JS代码。非常感谢。错误已删除，但按钮仍不工作。按钮未更改背景或主体的颜色

var parentElement = document.getElementById('deviceready');
var listeningElement = parentElement.querySelector('.listening');

// TODO: Cordova has been loaded. Perform any initialization that requires Cordova here.
var parentElement = document.getElementById('deviceready');
var listeningElement = parentElement.querySelector('.listening');
var receivedElement = parentElement.querySelector('.received');
listeningElement.setAttribute('style', 'display:none;');
receivedElement.setAttribute('style', 'display:block;');

var listeningElement = parentElement.querySelector('.listening');
var receivedElement = parentElement.querySelector('.received');
listeningElement.setAttribute('style', 'display:none;');
receivedElement.setAttribute('style', 'display:block;');