Question

尝试通过地理位置测量距离，脚本会在我的Galaxy s3上每13秒自动更新一次我想知道脚本的哪一部分会触发更新时间，如何让它像每一秒一样更快地更新。

window.onload = function () {
    var startPos;

    if (navigator.geolocation) {
        navigator.geolocation.getCurrentPosition(function (position) {
            startPos = position;
            document.getElementById("startLat").innerHTML = startPos.coords.latitude;
            document.getElementById("startLon").innerHTML = startPos.coords.longitude;
        }, function (error) {
            alert("Error occurred. Error code: " + error.code);
            // error.code can be:
            //   0: unknown error
            //   1: permission denied
            //   2: position unavailable (error response from locaton provider)
            //   3: timed out
        });

        navigator.geolocation.watchPosition(function (position) {
            document.getElementById("currentLat").innerHTML = position.coords.latitude;
            document.getElementById("currentLon").innerHTML = position.coords.longitude;
            document.getElementById("distance").innerHTML = calculateDistance(startPos.coords.latitude, startPos.coords.longitude,
            position.coords.latitude, position.coords.longitude);
        });
    }
};

// Reused code - copyright Moveable Type Scripts - retrieved May 4, 2010.
// http://www.movable-type.co.uk/scripts/latlong.html
// Under Creative Commons License http://creativecommons.org/licenses/by/3.0/
function calculateDistance(lat1, lon1, lat2, lon2) {
    var R = 6371; // km
    var dLat = (lat2 - lat1).toRad();
    var dLon = (lon2 - lon1).toRad();
    var a = Math.sin(dLat / 2) * Math.sin(dLat / 2) + Math.cos(lat1.toRad()) * Math.cos(lat2.toRad()) * Math.sin(dLon / 2) * Math.sin(dLon / 2);
    var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
    var d = R * c;
    return d;
}
Number.prototype.toRad = function () {
    return this * Math.PI / 180;
}

View The whole code here

Answer 1

目前的API无法做到这一点。见documentation here

Geolocation.watchPosition（）方法用于注册处理程序函数，每当设备位置发生变化时将自动调用。您也可以选择指定错误处理回调函数。

重点是我的。

您不需要每秒轮询该位置，它应该在位置自动更改时通知您。

您还应该能够启用highAccuracy模式以获得最佳效果：

options = {
  enableHighAccuracy: true,
};

id = navigator.geolocation.watchPosition(success, error, options);

为什么此代码每13秒更新一次？

1 个答案: