我的rails app上有以下JavaScript，我只想在cookie不存在时运行它。
function getGeoLocation() {
navigator.geolocation.getCurrentPosition(setGeoCookie);
}
function setGeoCookie(position) {
var cookie_val = position.coords.latitude + "|" + position.coords.longitude;
document.cookie = "lat_lng=" + escape(cookie_val);
}
我正在使用它来调用我的rails app上的脚本：
<%- unless @lat_lng %>
<script>
getGeoLocation();
</script>
<%- end %>
更新
我根据@Njdhv答案更新了我的application.js文件，但仍然显示弹出窗口。这是我做的：
function getCookieByName(name) {
var parts = document.cookie.split('; '),
len = parts.length,
item, i, ret;
for (i = 0; i < len; ++i) {
item = parts[i].split('=');
if (item[0] === name) {
ret = item[1];
return ret ? unescape(ret) : '';
}
}
return null;
}
if(getCookieByName('lat_lng') != null){
console.log('lat_lng')
function getGeoLocation() {
navigator.geolocation.getCurrentPosition(setGeoCookie);
}
function setGeoCookie(position) {
var cookie_val = position.coords.latitude + "|" + position.coords.longitude;
document.cookie = "lat_lng=" + escape(cookie_val);
}
}else{
//you can put your logic here...
}
答案 0 :(得分：2)
我发现问题是什么，我必须在我的观点中改变这一点：
来自：
<%- unless @lat_lng %>
<script>
getGeoLocation();
</script>
<%- end %>
到此：
<% if cookies[:lat_lng].nil? %>
<script>
getGeoLocation();
</script>
<% end %>
答案 1 :(得分：0)
当您保存多个Cookie时，您的搜索Cookie可能不是Cookie数组中的第一个ccokie，您必须同时搜索“lat_lng”和“lat_lng”。
var lat_lng;
if (navigator.cookieEnabled) {
cookieArray = document.cookie.split(";");
cookieArray.forEach(myFunction);
console.log(cookieArray)
function myFunction(item, index) {
if (item.split("=")[0] == " lat_lng" || item.split("=")[0] == "lat_lng") {
lat_lng = item.split("=")[1];
console.log("lat_lng " + lat_lng)
}
}
}
if(lat_lng == null){
//what you want to happen
}
答案 2 :(得分：0)
您可以使用{cure}位置的document.cookie读取所有Cookie。
根据您的要求，您需要在read中使用write和application Cookie，以便为cockie get创建自己的Singleton
，{{ 1}}和set（删除）。
Singleton 模式将特定对象的实例数限制为一个。这个单一实例称为单例。
下面我创建了一个 Singleton 名称为clear
cookieUtility获取cookie的如何使用它？
1）
var cookieUtility = (function() {
return {
/**
* Creates a cookie with the specified name and value. Additional settings for the cookie may be optionally specified
* (for example: expiration, access restriction, SSL).
* @param {String} name The name of the cookie to set.
* @param {Object} value The value to set for the cookie.
* @param {Object} [expires] Specify an expiration date the cookie is to persist until. Note that the specified Date
* object will be converted to Greenwich Mean Time (GMT).
* @param {String} [path] Setting a path on the cookie restricts access to pages that match that path. Defaults to all
* pages ('/').
* @param {String} [domain] Setting a domain restricts access to pages on a given domain (typically used to allow
* cookie access across subdomains). For example, "sencha.com" will create a cookie that can be accessed from any
* subdomain of sencha.com, including www.sencha.com, support.sencha.com, etc.
* @param {Boolean} [secure] Specify true to indicate that the cookie should only be accessible via SSL on a page
* using the HTTPS protocol. Defaults to false. Note that this will only work if the page calling this code uses the
* HTTPS protocol, otherwise the cookie will be created with default options.
*/
set: function(name, value) {
var argv = arguments,
argc = arguments.length,
expires = (argc > 2) ? argv[2] : null,
path = (argc > 3) ? argv[3] : '/',
domain = (argc > 4) ? argv[4] : null,
secure = (argc > 5) ? argv[5] : false;
document.cookie = name + "=" + escape(value) + ((expires === null) ? "" : ("; expires=" + expires.toUTCString())) + ((path === null) ? "" : ("; path=" + path)) + ((domain === null) ? "" : ("; domain=" + domain)) + ((secure === true) ? "; secure" : "");
},
/**
* Retrieves cookies that are accessible by the current page. If a cookie does not exist, `get()` returns null. The
* following example retrieves the cookie called "valid" and stores the String value in the variable validStatus.
*
*
* @param {String} name The name of the cookie to get
* @return {Object} Returns the cookie value for the specified name;
* null if the cookie name does not exist.
*/
get: function(name) {
var parts = document.cookie.split('; '),
len = parts.length,
item, i, ret;
// In modern browsers, a cookie with an empty string will be stored:
// MyName=
// In older versions of IE, it will be stored as:
// MyName
// So here we iterate over all the parts in an attempt to match the key.
for (i = 0; i < len; ++i) {
item = parts[i].split('=');
if (item[0] === name) {
ret = item[1];
return ret ? unescape(ret) : '';
}
}
return null;
},
/**
* Removes a cookie with the provided name from the browser
* if found by setting its expiration date to sometime in the past.
* @param {String} name The name of the cookie to remove
* @param {String} [path] The path for the cookie.
* This must be included if you included a path while setting the cookie.
*/
clear: function(name, path) {
if (this.get(name)) {
path = path || '/';
document.cookie = name + '=' + '; expires=Thu, 01-Jan-1970 00:00:01 GMT; path=' + path;
}
}
}
})();
2）
cookieUtility.get('name')//need to pass cookie name
3）用于删除Cookie
cookieUtility.set('name','value')//need to pass cookie name and value of cookie
答案 3 :(得分：-1)
javascript文档很好地解释了这一点。
使用document.cookie，您可以检查是否存在Cookie。
简单地将它与if语句组合起来就像这样：
if (document.cookie == null) {
// do nothing
}
else {
// run it!
}