要等到某个条件为真？
要等到某个条件为真？
提问于 2011-08-25 23:40:08
我在JavaScript中使用navigator.geolocation.watchPosition，我想要一种方法来处理这样一种可能性，即用户可能会在watchPosition找到自己的位置之前提交依赖于位置的表单。
理想情况下，用户会定期看到“等待位置”消息，直到获得位置，然后表单才会提交。
但是，考虑到它缺少wait函数，我不确定如何在JavaScript中实现它。
当前代码：
var current_latlng = null;
function gpsSuccess(pos){
//console.log('gpsSuccess');
if (pos.coords) {
lat = pos.coords.latitude;
lng = pos.coords.longitude;
}
else {
lat = pos.latitude;
lng = pos.longitude;
}
current_latlng = new google.maps.LatLng(lat, lng);
}
watchId = navigator.geolocation.watchPosition(gpsSuccess,
gpsFail, {timeout:5000, maximumAge: 300000});
$('#route-form').submit(function(event) {
// User submits form, we need their location...
while(current_location==null) {
toastMessage('Waiting for your location...');
wait(500); // What should I use instead?
}
// Continue with location found...
});回答 7
Stack Overflow用户
回答已采纳
发布于 2011-08-25 23:45:59
您可以使用超时来尝试重新提交表单：
$('#route-form').submit(function(event) {
// User submits form, we need their location...
if(current_location==null) {
toastMessage('Waiting for your location...');
setTimeout(function(){ $('#route-form').submit(); }, 500); // Try to submit form after timeout
return false;
} else {
// Continue with location found...
}
});Stack Overflow用户
发布于 2013-02-11 20:16:49
就我个人而言，我使用封装setTimeout()的waitfor()函数
//**********************************************************************
// function waitfor - Wait until a condition is met
//
// Needed parameters:
// test: function that returns a value
// expectedValue: the value of the test function we are waiting for
// msec: delay between the calls to test
// callback: function to execute when the condition is met
// Parameters for debugging:
// count: used to count the loops
// source: a string to specify an ID, a message, etc
//**********************************************************************
function waitfor(test, expectedValue, msec, count, source, callback) {
// Check if condition met. If not, re-check later (msec).
while (test() !== expectedValue) {
count++;
setTimeout(function() {
waitfor(test, expectedValue, msec, count, source, callback);
}, msec);
return;
}
// Condition finally met. callback() can be executed.
console.log(source + ': ' + test() + ', expected: ' + expectedValue + ', ' + count + ' loops.');
callback();
}我通过以下方式使用我的waitfor()函数：
var _TIMEOUT = 50; // waitfor test rate [msec]
var bBusy = true; // Busy flag (will be changed somewhere else in the code)
...
// Test a flag
function _isBusy() {
return bBusy;
}
...
// Wait until idle (busy must be false)
waitfor(_isBusy, false, _TIMEOUT, 0, 'play->busy false', function() {
alert('The show can resume !');
});Stack Overflow用户
发布于 2011-08-25 23:43:40
您将希望使用setTimeout
function checkAndSubmit(form) {
var location = getLocation();
if (!location) {
setTimeout(checkAndSubmit, 500, form); // setTimeout(func, timeMS, params...)
} else {
// Set location on form here if it isn't in getLocation()
form.submit();
}
}..。在那里getLocation会查到你的位置。
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原文链接：
https://stackoverflow.com/questions/7193238
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