我在 onDeviceReady 中添加了一个事件监听器来监听后退按钮事件，并在按下时用 stopWatch 进行响应。但是，它会在应用程序启动时做出响应。
<!DOCTYPE html>
<html>
<head>
<title>UNH BSApp</title>
<script type="text/javascript" charset="utf-8" src="phonegap.js"></script>
<script type="text/javascript" charset="utf-8">
// The watch id references the current `watchAcceleration`
var watchID = null;
// Wait for PhoneGap to load
//
document.addEventListener("deviceready", onDeviceReady, false);
// PhoneGap is ready
//
function onDeviceReady() {
document.addEventListener("backbutton", stopWatch(), false);
startWatch();
}
// Start watching the acceleration
//
function startWatch() {
document.addEventListener("menubutton", stopWatch(), false);
// Update acceleration every 0.1 seconds
var options = { frequency: 10 };
watchID = navigator.accelerometer.watchAcceleration(onSuccess, onError, options);
}
// Stop watching the acceleration
//
function stopWatch() {
alert("Hello!");
if (watchID) {
navigator.accelerometer.clearWatch(watchID);
watchID = null;
}
}
// onSuccess: Get a snapshot of the current acceleration
//
function onSuccess(acceleration) {
var element = document.getElementById('accelerometer');
element.innerHTML = 'Acceleration X: ' + acceleration.x + '<br />' +
'Acceleration Y: ' + acceleration.y + '<br />' +
'Acceleration Z: ' + acceleration.z + '<br />' +
'Timestamp: ' + acceleration.timestamp + '<br />';
}
// onError: Failed to get the acceleration
//
function onError() {
alert('onError!');
}
</script>
<style>
#start {
display:block;
border:solid;
}
</style>
</head>
<body>
<div id="accelerometer">Waiting for accelerometer...</div>
<div id="start">Start</div>
</body>
</html>
最佳答案
document.addEventListener("menubutton", stopWatch(), false);
这会立即调用 stopWatch 函数。你想要这样的东西:
document.addEventListener("menubutton", stopWatch, false);
^^ no parens!
关于javascript - 为什么我的 JavaScript 代码会过早触发？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/9401296/