等到某个条件成立? [英] Wait until a condition is true?

问题描述

我在 JavaScript 中使用 navigator.geolocation.watchPosition，我想要一种方法来处理用户可能在 watchPosition 找到了它的位置.

I'm using navigator.geolocation.watchPosition in JavaScript, and I want a way to deal with the possibility that the user might submit a form relying on location before watchPosition has found its location.

理想情况下，用户会定期看到等待位置"消息，直到获得位置，然后提交表单.

Ideally the user would see a 'Waiting for location' message periodically until the location was obtained, then the form would submit.

但是，鉴于 JavaScript 缺少 wait 函数，我不确定如何在 JavaScript 中实现它.

However, I'm not sure how to implement this in JavaScript given its lack of a wait function.

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...
});

推荐答案

您可以使用超时尝试重新提交表单:

You could use a timeout to try to re-submit the form:

$('#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...
    }
});

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