Javascript KnockoutJS中的ViewModel无法访问全局变量
我正在使用KnockoutJS库开发一个简单的Google地图应用程序——或者至少它在概念上看起来足够简单。 在阅读了KnockoutJS并编写了一些示例之后,我将最初的部分放在了一起。到目前为止,html只是一张地图,我的目标是在我跨过第一个障碍后立即填充列表。困难在于Javascript。以下是代码供参考:Javascript KnockoutJS中的ViewModel无法访问全局变量,javascript,google-maps,google-maps-api-3,mvvm,knockout.js,Javascript,Google Maps,Google Maps Api 3,Mvvm,Knockout.js,我正在使用KnockoutJS库开发一个简单的Google地图应用程序——或者至少它在概念上看起来足够简单。 在阅读了KnockoutJS并编写了一些示例之后,我将最初的部分放在了一起。到目前为止,html只是一张地图,我的目标是在我跨过第一个障碍后立即填充列表。困难在于Javascript。以下是代码供参考: "use strict"; var map; var center; var defaultBounds; var placesServices; //LocationObject
"use strict";
var map;
var center;
var defaultBounds;
var placesServices;
//LocationObject created to hold data for locations generated from google.places.nearbySearch
var LocationObject = function(data){
this.position = data.geometry.location;
this.lat = data.geometry.location.lat;
this.lng = data.geometry.location.lng;
this.name = data.name;
this.placeID = data.place_id;
this.rating = data.rating;
this.types = data.types;
this.linkToPhoto = data.html_attributions;
};
function initMap(){
map = new google.maps.Map(document.getElementById('map'), {
center: center,
zoom: 17,
mapTypeId: 'satellite',
draggable: true,
zoomControl: false,
scrollwheel: true,
disableDoubleClickZoom: true
});
defaultBounds = new google.maps.LatLngBounds(
new google.maps.LatLng(47.614217, -122.317981),new google.maps.LatLng(47.612975, -122.316291));
map.fitBounds(defaultBounds);
placesServices = new google.maps.places.PlacesService(map);
}
//ViewModel created to observe changes on the map
var MapViewModel = function(){
var self = this;
self.testarr = ko.observableArray([
{ firstName: 'Bert', lastName: 'Bertington' },
{ firstName: 'Charles', lastName: 'Charlesforth' },
{ firstName: 'Denise', lastName: 'Dentiste' }
]);
self.locations = ko.observableArray([]);
self.markers = [];
this.getNearbyLocations = function(){
if(placesServices === undefined){
placesServices = new google.maps.places.PlacesService(map);
}
var request = {
location: center,
radius: getBoundsRadius(defaultBounds),
type: ['establishment']
};
placesServices.nearbySearch(request, function(results, status) {
if (status === google.maps.places.PlacesServiceStatus.OK) {
for (var i = 0; i <= 18; i++) {
var marker = new google.maps.Marker({
map: map,
position: results[i].geometry.location,
animation: google.maps.Animation.DROP
});
self.locations.push(new LocationObject(results[i]));
self.markers.push(marker);
}
} else{
alert("We were not able to find any nearby locations in this Neighbourhood.");
}
});
};
this.init = function(){
self.getNearbyLocations();
};
};
var myMapViewModel = new MapViewModel();
myMapViewModel.init();
ko.applyBindings(myMapViewModel);
/* Utility Functions */
function getBoundsRadius(bounds){....}
我不明白为什么它在这里没有被识别,当地图本身第一次加载时没有问题,但是在这里它被挂起了
以下是html供参考,但不应存在问题:
<!DOCTYPE html>
<html lang="en">
<head>
<!-- Required meta tags -->
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<!-- Per Google guideline scheduled for the M65 release, css has been moved to an importer -->
<link rel="import" href="importer.htm"></link>
<!-- Bootstrap CSS -->
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta/css/bootstrap.min.css" integrity="sha384-/Y6pD6FV/Vv2HJnA6t+vslU6fwYXjCFtcEpHbNJ0lyAFsXTsjBbfaDjzALeQsN6M" crossorigin="anonymous">
</head>
<body>
<div class="container-fluid">
<div class="row">
<div class="col-xs-12 col-md-4">
<!-- List goes in this column. -->
</div>
</div>
<div class="col-xs-12 col-md-8">
<!-- Map goes into this column. -->
<div id="map" style="width:100%;height:100vh;"></div>
</div>
</div>
</div>
<!-- jQuery first, then Popper.js, then Bootstrap JS -->
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.11.0/umd/popper.min.js" integrity="sha384-b/U6ypiBEHpOf/4+1nzFpr53nxSS+GLCkfwBdFNTxtclqqenISfwAzpKaMNFNmj4" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-beta/js/bootstrap.min.js" integrity="sha384-h0AbiXch4ZDo7tp9hKZ4TsHbi047NrKGLO3SEJAg45jXxnGIfYzk4Si90RDIqNm1" crossorigin="anonymous"></script>
<!-- Optional JavaScript -->
<script src="js/knockout.js" ></script>
<script src="js/app.js"></script>
<script async defer src="https://maps.googleapis.com/maps/api/js?key=AIzaSyC-1EdIyUOb74oGG_mEoPvJTAGCSJvSQms&callback=initMap&libraries=places"></script>
</body>
我还认为错误是因为你的app.js在maps脚本之前被调用。但是我试着改变它,同样的错误,我也试着删除user3297291的注释所建议的异步参数,仍然是同样的错误。理论上是这样的 但这很有效-将app.js代码的最后3行包装到一个ready函数中:
$(document).ready(function(){
var myMapViewModel = new MapViewModel();
myMapViewModel.init();
ko.applyBindings(myMapViewModel);
});
尝试在app.js之前添加maps脚本引用。您可能还想查看答案是的,我昨天也测试了所有这些备选方案,结果与您发现的相同。此外,由于映射正在加载并存储在全局声明的变量中,我认为它应该是可访问的。有一次,我尝试了一个实现,我将变量传递到相应的函数中,但结果相同。今晚我将添加jquery选项,并在确认后批准。我最终不得不在一个超时时间内完成它,但这让我足够接近了-谢谢!
$(document).ready(function(){
var myMapViewModel = new MapViewModel();
myMapViewModel.init();
ko.applyBindings(myMapViewModel);
});