Cordova 按两次退出程序

<script src="cordova.js"></script>
<script type="text/javascript" charset="utf-8">
// Wait for device API libraries to load    //
function onLoad() {
document.addEventListener("deviceready", onDeviceReady, false);
}
document.addEventListener("deviceready", onDeviceReady, false);

function onDeviceReady() {
//navigator.splashscreen.hide();
document.addEventListener("backbutton", onBackKeyDown, false);
}
function onBackKeyDown() {
window.plugins.toast.showLongCenter('再按一次退出', function(a){console.log('toast success: ' + a)}, function(b){alert('toast error: ' + b)})
document.removeEventListener("backbutton", onBackKeyDown, false); // 注销返回键
document.addEventListener("backbutton", exitApp, false);//绑定退出事件
// 3秒后重新注册
var intervalID = window.setInterval(function() {
window.clearInterval(intervalID);
document.removeEventListener("backbutton", exitApp, false); // 注销返回键
document.addEventListener("backbutton", onBackKeyDown, false); // 返回键
}, 3000);
}
function exitApp(){
navigator.app.exitApp();
}
</script>

cordova plugin add cordova-plugin-x-toast