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+---
+title: GeolocationCoordinates.longitude
+slug: Web/API/GeolocationCoordinates/longitude
+tags:
+  - API
+  - GPS
+  - Geolocation
+  - Geolocation API
+  - GeolocationCoordinates
+  - Global Positioning System
+  - Property
+  - Read-only
+  - Reference
+  - Secure context
+  - longitude
+browser-compat: api.GeolocationCoordinates.longitude
+---
+{{securecontext_header}}{{APIRef("Geolocation API")}}
+
+The {{domxref("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 {{domxref("DOMTimeStamp")}} indicating a time of measurement,
+the `GeolocationCoordinates` object is part of the
+{{domxref("GeolocationPosition")}} interface, which is the object type returned by
+Geolocation API functions that obtain and return a geographical position.
+
+## Syntax
+
+```js
+let longitude = geolocationCoordinatesInstance.longitude
+```
+
+### Value
+
+The value in `longitude` is the geographical longitude of the location on
+Earth described by the `Coordinates` object, in decimal degrees. The value is
+defined by the World Geodetic System 1984 specification (WGS 84).
+
+> **Note:** The zero meridian (also known as the prime meridian or the
+> reference meridian) is not precisely the same as the Greenwich meridian that most
+> people think of. It is, instead, the {{interwiki("wikipedia", "IERS Reference
+    Meridian")}}, which is located 5.3 {{interwiki("wikipedia", "arcseconds")}} (102
+> meters / 335 feet) east of the {{interwiki("wikipedia", "Greenwich meridian")}}. This
+> is the same standard used by the {{interwiki("wikipedia", "Global Positioning
+    System")}} (GPS).
+
+## Examples
+
+In this simple example, we fetch the user's location and display the resulting
+coordinates once they're returned.
+
+### JavaScript
+
+The JavaScript code below creates an event listener so that when the user clicks on a
+button, the location information is retrieved and displayed.
+
+```js
+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 longitude will be drawn, the event listener is
+established by calling {{domxref("EventTarget.addEventListener", "addEventListener()")}}
+on the {{HTMLElement("button")}} element. When the user clicks the button, we'll fetch
+and display the location information.
+
+Upon receiving a {{event("click")}} event, we call
+{{domxref("Geolocation.getCurrentPosition", "getCurrentPosition()")}} to request the
+device's current position. This is an asynchronous request, so we provide a callback
+which receives as in put a {{domxref("GeolocationPosition")}} object describing the
+determined position.
+
+From the `GeolocationPosition` object, we obtain the user's latitude and
+longitude using {{domxref("GeolocationCoordinates/latitude", "position.coords.latitude")}} and
+`position.coords.longitude` so we can update the displayed coordinates. The
+two {{HTMLElement("span")}} elements are updated to display the corresponding values
+after being converted to a value with two decimal places.
+
+### HTML
+
+The HTML used to present the results looks like this:
+
+```html
+<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>
+```
+
+### Result
+
+Take this example for a test drive here:
+
+{{EmbedLiveSample("Examples", 600, 120)}}
+
+## Specifications
+
+{{Specifications}}
+
+## Browser compatibility
+
+{{Compat}}
+
+## See also
+
+- [Using the Geolocation API](/en-US/docs/Web/API/Geolocation_API/Using_the_Geolocation_API)
+- The {{domxref("GeolocationCoordinates")}} interface it belongs to.
+- The {{domxref("GeolocationPosition")}} interface, which is the top-level interface
+  used to return geolocation data from the Geolocation API functions
+  {{domxref("Geolocation.getCurrentPosition()")}} and
+  {{domxref("Geolocation.watchPosition", "watchPosition()")}}.