我的JavaScript（下方）非常不整洁，并且包含错误，我无法解决。错误在showPosition函数中（我在函数中有一个函数，不推荐使用）。
我刚刚开始尝试使用JavaScript，所以如果这是一个简单的问题我会道歉。我还提供了一个jsFiddle of my JavaScript，它突出了我坚持使用的区域（http://jsfiddle.net/dnUTx/）。
在jsFiddle中，我在第25行遇到错误 - '函数声明不应放在块中。
非常感谢任何帮助。
// JavaScript Document
var x = document.getElementById("info");
function getLocation() {
if (navigator.geolocation) {
navigator.geolocation.watchPosition(showPosition, showError, clearWatch, {
enableHighAccuracy: true,
maximumAge: 30000,
timeout: 30000
});
} else {
x.innerHTML = "Your browser does not support the geolocation () API.";
}
}
var flightPathCoordinates = [];
var lat1, lng1, first_check = false;
function showPosition(position) {
if (!first_check) {
lat1 = position.coords.latitude;
lng1 = position.coords.longitude;
first_check = true;
} else {
function distanceFrom(points) {
var lat1 = points.lat1;
var radianLat1 = lat1 * (Math.PI / 180);
var lng1 = points.lng1;
var radianLng1 = lng1 * (Math.PI / 180);
var lat2 = points.lat2;
var radianLat2 = lat2 * (Math.PI / 180);
var lng2 = points.lng2;
var radianLng2 = lng2 * (Math.PI / 180);
var earth_radius = 3959; // or 6371 for kilometers
var diffLat = (radianLat1 - radianLat2);
var diffLng = (radianLng1 - radianLng2);
var sinLat = Math.sin(diffLat / 2);
var sinLng = Math.sin(diffLng / 2);
var a = Math.pow(sinLat, 2.0) + Math.cos(radianLat1) * Math.cos(radianLat2) * Math.pow(sinLng, 2.0);
var distance = earth_radius * 2 * Math.asin(Math.min(1, Math.sqrt(a)));
return distance.toFixed(3);
}
var distance = distanceFrom({
"lat1": lat1,
"lng1": lng1,
"lat2": position.coords.latitude,
"lng2": position.coords.longitude
});
}
x.innerHTML = "Latitude: " + position.coords.latitude +
"<br>Longitude: " + position.coords.longitude +
"<br>Accuracy: " + position.coords.accuracy +
"<br>Altitude: " + position.coords.altitude +
"<br>Altitude Accuracy: " + position.coords.altitudeAccuracy +
"<br>Heading: " + position.coords.heading +
"<br>Speed (km): " + position.coords.speed * 3.6 +
"<br>Timestamp: " + new Date(position.timestamp).toLocaleString() +
"<br>Distance Travelled (km): " + distance +
"<br>Stopwatch: " + min + ":" + sec + ":" + msec;
lat = position.coords.latitude;
lon = position.coords.longitude;
latlon = new google.maps.LatLng(lat, lon);
mapholder = document.getElementById('mapholder');
var myOptions = {
center: latlon,
zoom: 16,
mapTypeId: google.maps.MapTypeId.ROADMAP,
mapTypeControl: true,
navigationControlOptions: {
style: google.maps.NavigationControlStyle.SMALL
}
};
var map = new google.maps.Map(document.getElementById("mapholder"), myOptions);
//Bicycle Store
var request = {
location: (latlon),
radius: '1000',
types: ['bicycle_store']
};
infowindow = new google.maps.InfoWindow();
var service = new google.maps.places.PlacesService(map);
service.nearbySearch(request, callback);
function callback(results, status) {
if (status == google.maps.places.PlacesServiceStatus.OK) {
for (var i = 0; i < results.length; i++) {
var place = results[i];
createMarker(results[i]);
}
}
}
function createMarker(place) {
var placeLoc = place.geometry.location;
//Custom Marker 1
var image1 = '../images/logo_marker1.png';
var marker1 = new google.maps.Marker({
position: place.geometry.location,
map: map,
icon: image1,
title: "Bicycle Store"
});
google.maps.event.addListener(marker1, 'click', function () {
infowindow.setContent(place.name);
infowindow.open(map, this);
});
}
//Bicycle Layer
var bikeLayer = new google.maps.BicyclingLayer();
bikeLayer.setMap(map);
//Custom Marker 2
var image2 = '../images/logo_marker2.png';
var marker2 = new google.maps.Marker({
position: latlon,
map: map,
icon: image2,
title: "You are here!"
});
//Panoramio Layer
var panoramioLayer = new google.maps.panoramio.PanoramioLayer();
panoramioLayer.setUserId("7467601");
panoramioLayer.setMap(map);
google.maps.event.addListener(panoramioLayer, 'click', function (event) {
var attribution = document.createTextNode(event.featureDetails.title + ": " + event.featureDetails.author);
var br = document.createElement("br");
var link = document.createElement("a");
link.setAttribute("href", event.featureDetails.url);
link.appendChild(attribution);
});
//Polyline Layer
flightPathCoordinates.push(new google.maps.LatLng(position.coords.latitude, position.coords.longitude));
var flightPath = new google.maps.Polyline({
path: flightPathCoordinates,
strokeColor: "#FF0000",
strokeOpacity: 1.0,
strokeWeight: 2
});
flightPath.setMap(map);
}
function showError(error) {
switch (error.code) {
case error.PERMISSION_DENIED:
x.innerHTML = "User denied the request for Geolocation.";
break;
case error.POSITION_UNAVAILABLE:
x.innerHTML = "Location information is unavailable.";
break;
case error.TIMEOUT:
x.innerHTML = "The request to get user location timed out.";
break;
case error.UNKNOWN_ERROR:
x.innerHTML = "An unknown error occurred.";
break;
}
}
function clearWatch() {
navigator.geolocation.clearWatch(showPosition);
}
答案 0 :(得分：2)
嗯，对我来说问题非常明确，甚至为新成员提供了一个jsfiddle，+。
你的问题是双重的：
您使用本地变量distance来构建x.innerHTML字符串。
但是，distance仅在if语句的else子句中定义（精确分配）。
其次，在块{}中使用'函数声明'，这在语法上是非法的！这是因为Blocks只能包含StateDeclaration所声明的语句，而不是SourceElements
因此，在if / else / while / for块中，你必须使用'函数表达式';
例如：var identifier=function(//args){//code};
这就是JSFiddle中JSHint给出的错误消息的原因。
请参阅this fiddle update以查看我的更改（只是让jshint验证，但由于这只是某些代码的一部分，因此我无法再进行尝试）。
我在您的函数var distance=0中的第一个if - 子句之前添加了showPosition作为局部变量，并将function declaration更改为function expression内的else {1}} - 条款