安全上下文
此特征只可用于
安全上下文
(HTTPS)，在某些或所有
支持浏览器
.
GeolocationCoordinates
interface's read-only
longitude
property is a double-precision floating point value which represents the longitude of a geographical position, specified in decimal degrees. Together with a
DOMTimeStamp
indicating a time of measurement, the
GeolocationCoordinates
object is part of the
GeolocationPosition
interface, which is the object type returned by Geolocation API functions that obtain and return a geographical position.
let longitude = geolocationCoordinatesInstance.longitude
The value in
longitude
is the geographical longitude of the location on Earth described by the
坐标
object, in decimal degrees. The value is defined by the World Geodetic System 1984 specification (WGS 84).
注意 : The zero meridian (also known as the prime meridian or the reference meridian) is not precisely the same as the Greenwhich meridian that most people think of. It is, instead, the IERS Reference Meridian , which is located 5.3 arcseconds (102 meters / 335 feet) east of the Greenwich meridian . This is the same standard used by the Global Positioning System (GPS).
In this simple example, we fetch the user's location and display the resulting coordinates once they're returned.
The JavaScript code below creates an event listener so that when the user clicks on a button, the location information is retrieved and displayed.
let button = document.getElementById("get-location");
let latText = document.getElementById("latitude");
let longText = document.getElementById("longitude");
button.addEventListener("click", function() {
navigator.geolocation.getCurrentPosition(function(position) {
let lat = position.coords.latitude;
let long = position.coords.longitude;
latText.innerText = lat.toFixed(2);
longText.innerText = long.toFixed(2);
});
});
After setting up variables to more conveniently reference the button element and the two elements into which the latitude and logitude will be drawn, the event listener is established by calling
addEventListener()
在
<button>
element. When the user clicks the button, we'll fetch and display the location information.
Upon receiving a
click
event, we call
getCurrentPosition()
to request the device's current position. This is an asynchronous request, so we provide a callback which receives as in put a
GeolocationPosition
object describing the determined position.
从
GeolocationPosition
object, we obtain the user's latitude and longitude using
position.coords.latitude
and
position.coords.longitude
so we can update the displayed coordinates. The two
<span>
elements are updated to display the corresponding values after being converted to a value with two decimal places.
The HTML used to present the results looks like this:
<p> Your location is <span id="latitude">0.00</span>° latitude by <span id="longitude">0.00</span>° longitude. </p> <button id="get-location"> Get My Location </button>
Take this example for a test drive here:
| 规范 | 状态 | 注释 |
|---|---|---|
|
地理位置 API
The definition of 'Coordinates.longitude' in that specification. |
推荐 | 最初的规范。 |
| 桌面 | 移动 | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
longitude
|
Chrome 5 | Edge 12 | Firefox 3.5 | IE 9 |
Opera
16
|
Safari 5 | WebView Android 37 | Chrome Android 18 | Firefox Android 4 |
Opera Android
16
|
Safari iOS ? | Samsung Internet Android 1.0 |
完整支持
兼容性未知
GeolocationCoordinates
interface it belongs to.
GeolocationPosition
interface, which is the top-level interface used to return geolocation data from the Geolocation API functions
Geolocation.getCurrentPosition()
and
watchPosition()
.
GeolocationCoordinates