在发布这个问题之前，我阅读了几个主题，不幸的是我找不到适合我的问题的答案。
这是我的代码片段
<html>
<head>
<meta name="viewport" content="initial-scale=1.0, user-scalable=no">
<meta charset="utf-8">
<!--<script src="https://maps.googleapis.com/maps/api/js?v=3.exp&sensor=false&libraries=places"></script>
<script src="http://goessner.net/download/prj/jsonxml/xml2json.js"></script>
-->
<script type="text/javascript" src="https://maps.googleapis.com/maps/api/js?key=AIzaSyB1Wwh21ce7jnB6yDbjVGN3LC5ns7OoOL4&sensor=false">
</script>
<link rel="stylesheet" type="text/css" href="bd_css">
<!-- javascript code for triggering the download for csv file of businesses-->
<script type="text/javascript">
function populateIframe(id)
{
var ifrm = document.getElementById(id);
ifrm.src = "business_data_to_excel";
}
</script>
<script>
function showCategories(str)
{
if (window.XMLHttpRequest)
{// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp=new XMLHttpRequest();
}
else
{// code for IE6, IE5
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange=function()
{
if (xmlhttp.readyState==4 && xmlhttp.status==200)
{
document.getElementById("txt").innerHTML=xmlhttp.responseText;
}
}
// here within this bd_get_subcategories we have to
xmlhttp.open("GET","bd_get_subcategories?q="+str,true);
xmlhttp.send();
loadMap(str);
}
</script>
<!-- Rohit Script ---------------------->
<script type="text/javascript">
var map, actual, iw;
var gmarkers = [];
var icons = {
img: "http://sites.google.com/site/mxamples/icons-dot.png",
bar: [0, 0],
cafe: [128, 32],
hotel: [32, 32],
disco: [96, 0],
white: [192, 0]
};
function shifter(a) {
var g = google.maps;
var b = {
url: icons.img,
size: new g.Size(32, 32),
origin: new g.Point(a[0], a[1]),
anchor: new g.Point(15, 32)
};
return b
}
function createMarker(b, c, d, e, f) {
var g = google.maps;
var h = shifter(icons[e]);
var i = new g.Marker({
position: b,
map: map,
title: c,
clickable: true,
draggable: false,
icon: h
});
i.category = e;
i.name = c;
i.id = f;
gmarkers.push(i);
var j = "<b>" + c + "<\/b><p>" + d + "<\/p>";
g.event.addListener(i, "click", function () {
iw.setContent(j);
iw.open(map, this)
});
g.event.addListener(i, "mouseover", function () {
i.setIcon(shifter(icons.white));
var a = document.getElementById(f);
if (a) {
a.className = "focus";
actual = a
}
});
g.event.addListener(i, "mouseout", function () {
i.setIcon(shifter(icons[e]));
if (actual) {
actual.className = "normal"
}
})
}
var hover = {
over: function (i) {
var a = gmarkers[i];
var b = document.getElementById(a.id);
b.className = "focus";
a.setIcon(shifter(icons.white))
},
out: function (i) {
var a = gmarkers[i];
var b = document.getElementById(a.id);
b.className = "normal";
a.setIcon(shifter(icons[a.category]))
}
};
var visible = {
show: function (a) {
for (var i = 0, m; m = gmarkers[i]; i++) {
if (m.category == a) {
m.setVisible(true)
}
}
document.getElementById(a).checked = true
},
hide: function (a) {
for (var i = 0, m; m = gmarkers[i]; i++) {
if (m.category == a) {
m.setVisible(false)
}
}
document.getElementById(a).checked = false;
iw.close()
}
};
function boxclick(a, b) {
if (a.checked) {
visible.show(b)
} else {
visible.hide(b)
}
makeSidebar()
}
function triggerClick(i) {
google.maps.event.trigger(gmarkers[i], "click")
}
function makeSidebar() {
var a;
var b = "";
for (var i = 0, m; m = gmarkers[i]; i++) {
if (m.getVisible()) {
var c = gmarkers[i].category;
c = c.replace(/^./, c.charAt(0).toUpperCase());
if (a != c) b += "<b>" + c + "s<\/b><br \/>";
b += '<a id="' + gmarkers[i].id + '" href="javascript:triggerClick(' + i + ')" onmouseover="hover.over(' + i + ')" onmouseout="hover.out(' + i + ')">' + gmarkers[i].name + '<\/a><br \/>';
a = c
}
}
document.getElementById("sidebar").innerHTML = b
}
function loadMap() {
var g = google.maps;
var a = {
center: new g.LatLng(48.139543, 11.571436),
zoom: 14,
mapTypeId: g.MapTypeId.ROADMAP,
mapTypeControlOptions: {
mapTypeIds: [g.MapTypeId.ROADMAP, g.MapTypeId.SATELLITE, g.MapTypeId.HYBRID]
},
panControl: true,
zoomControl: true
};
map = new g.Map(document.getElementById("map"), a);
iw = new g.InfoWindow();
g.event.addListener(map, "click", function () {
if (iw) iw.close()
});
readData()
}
function readData() {
var k;
try {
if (typeof ActiveXObject != "undefined") {
k = new ActiveXObject("Microsoft.XMLHTTP")
} else if (window["XMLHttpRequest"]) {
k = new XMLHttpRequest()
}
} catch (e) {}
k.open("GET", "marker_info_to_xml?p=bar", true);
k.onreadystatechange = function () {
if (k.readyState == 4) {
var a = k.responseXML;
var b = a.documentElement.getElementsByTagName("marker");
for (var i = 0, m; m = b[i]; i++) {
var c = parseFloat(m.getAttribute("lat"));
var d = parseFloat(m.getAttribute("lng"));
var e = new google.maps.LatLng(c, d);
var f = m.getAttribute("address");
var g = m.getAttribute("nr");
var h = m.getAttribute("name");
var j = m.getAttribute("category");
createMarker(e, h, f, j, g)
}
if (gmarkers) {
gmarkers.sort(compareCats)
}
visible.show("bar");
visible.show("cafe");
visible.hide("hotel");
visible.hide("disco");
makeSidebar()
}
};
k.send(null)
}
var compareCats = function (a, b) {
var c = a.name;
c = c.toLowerCase();
c = c.replace(/ä/g, "a");
c = c.replace(/ö/g, "o");
c = c.replace(/ü/g, "u");
c = c.replace(/ß/g, "s");
var d = b.name;
d = d.toLowerCase();
d = d.replace(/ä/g, "a");
d = d.replace(/ö/g, "o");
d = d.replace(/ü/g, "u");
d = d.replace(/ß/g, "s");
var e = a.category;
var f = b.category;
if (a.category == b.category) {
if (a.name == b.name) {
return 0
}
return (a.name < b.name) ? -1 : 1
}
return (a.category < b.category) ? -1 : 1
};
//window.onload = loadMap;
google.maps.event.addDomListener(window, "load", loadMap);
</script>
<!-- Rohit SCript end -------------------->
</head>
<body>
<div id="business_form"><form action= "">
<div id='radiobtn'>Search By:
<input type="radio">Title
<input type="radio">Keywords
<input type="radio">Both
</div></br>
<div id="searchfor">Search For:
<td><input type="text" maxlength="30"></td>
<td><input type="submit" name="submit_query" value="Search"></td>
<iframe id="frame1" style="display:none"></iframe>
<a href="javascript:populateIframe('frame1')">Download entire directory in Excel format</a>
</div></br>
<div id='cat_select'>Catgories:<select name='users' onchange='showCategories(this.value)'>
<?php
$query_select = ee()->db->query('SELECT DISTINCT category_name,cat_counter FROM stab_num_of_cat_subcat');
echo "<option value=''>All Categories</option>";
foreach($query_select->result_array() as $row_value){
echo "<option value='".$row_value['category_name']."'>".$row_value['category_name']."(".$row_value['cat_counter'].")</option>";
}
?>
</select></div>
</form></div>
<div id="txt">Sub Categories:<select disabled name="subcat_select"><option value=''>All Subcategories</option></select></div></br>
<div id="map-canvas" style="width:500px;height:380px;">
</body>
</html>
基本上，在更改类别后，我尝试渲染地图，并从 xml 文件获取数据。
但我收到错误“Uncaught TypeError: Cannot read property 'offsetWidth' of null”并且我的地图未加载。
我的例子与“http://www.wolfpil.de/v3/toggle-cats.html http://www.wolfpil.de/v3/toggle-cats.html"
我不知道我在这里做错了什么。
请帮帮我。
