I'm trying to figure out the best fallback method for storing data when someone visits our site. We use this to store search filter preferences in particular, that need to move across the site as they move around. Ideally it would work with:
localStorage first
fallback to sessionStorage
then fallback to cookies
My current setup looks a bit like:
var localStorageAvail = supports_html5_storage();
var storage = "local";
if (localStorageAvail == undefined || localStorageAvail == false || localStorageAvail == null) {
storage = "cookie";
}
function supports_html5_storage() {
var testKey = 'test', storage = window.localStorage;
try {
storage.setItem(testKey, '1');
storage.removeItem(testKey);
return true;
} catch (error) {
return false;
}
}
function getValue(what) {
if (storage == "cookie") {
// get from cookie
return readCookie(what);
} else {
// localstorage
return localStorage.getItem(what)
}
}
function setValue(what,value) {
if (storage == "cookie") {
// get from cookie
writeCookie(what,value,365);
} else {
// localstorage
localStorage.setItem(what,value)
}
}
function readCookie(name) {
var nameEQ = name + "=";
var ca = document.cookie.split(';');
for(var i=0;i < ca.length;i++) {
var c = ca[i];
while (c.charAt(0)==' ') c = c.substring(1,c.length);
if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
}
return null;
}
function writeCookie(name,value,days) {
var expires;
if (days) {
var date = new Date();
date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000));
expires = "; expires=" + date.toGMTString();
}
else {
expires = "";
}
document.cookie = name + "=" + value + expires + "; path=/";
}
FWIW, I'm not using jQuery, and I don't want to have to include extra libraries to do this. It needs to all be in Vanilla JS :)
My question: What is the best way to do this? Should I just tweak my current method, so it includes sessionStorage as well? Or are there better methods to do this?
If the text We are sorry but we made a boo boo appears then
Wait 5 seconds
reload
I would like to do this in JavaScript.
Here is an attempt
(function () {
"use strict";
function walkTheDOM(node, func) {
if (node && node.nodeType) {
if (typeof func === "function") {
func(node);
}
node = node.firstChild;
while (node) {
walkTheDOM(node, func);
node = node.nextSibling;
}
}
}
function filterElementsByContains(elements, string) {
var toStringFN = {}.toString,
text = toStringFN.call(elements),
result,
length,
i,
element;
if (text !== "[object NodeList]" && text !== "[object Array]" && !($() instanceof jQuery)) {
return result;
}
result = [];
if (typeof string === "string") {
string = new RegExp("^" + string + "$");
} else if (toStringFN.call(string) !== "[object RegExp]") {
return result;
}
function getText(node) {
if (node.nodeType === 3) {
text += node.nodeValue;
}
}
length = elements.length;
i = 0;
while (i < length) {
text = "";
element = elements[i];
walkTheDOM(element, getText);
if (string.test(text)) {
result.push(element);
}
i += 1;
}
return result;
}
if(filterElementsByContains([document.getElementsByTagName("table")[0]], /We are sorry but we made a boo boo/).length) {
location.reload();
}
The above could should, I think, work for the text if it appears in a specific place. I want to make it more general - so that the text could appear anywhere on that page.
Also, I would like to know how to add a pause so that, for example, it waits 5 seconds before reloading.
I guess I would add incorporate something like:
setTimeout(
function()
{
//location.reload();
}, 5000);
Just do an indexOf on the body's textContent/innerText property
var content = document.body.textContent || document.body.innerText;
var hasText = content.indexOf("We are sorry but we made a boo boo")!==-1;
if(hasText){
setTimeout(function(){
window.location = "http://www.example.com";
},5000);
}
This may work:
var bodyText = document.body.textContent || document.body.innerText;
var msg = "We are sorry but we made a boo boo";
if (bodyText.indexOf(msg) > -1) {
setTimeout(function() {
location.reload();
}, 5000);
}
--sorry for nearly duplicate answer :\ --
--edit--
Tell me - how can I add a second rule, it's a different way of
phrasing the error message: There was an internal error in our system.
We logged the problem and will investigate it later.
This will check for both messages:
var bodyText = document.body.textContent || document.body.innerText;
var msg = [
"We are sorry but we made a boo boo",
"There was an internal error in our system. We logged the problem and will investigate it later."
];
var flag = false;
for (var i = 0; i < msg.length; i++) {
if bodyText.indexOf(msg[i]) {
flag = true;
}
}
if (flag) {
setTimeout(function() {
location.reload();
}, 5000);
}
Explanation: All I did was modify msg to be an array of strings rather than a string itself. Then for every msg we want to check, we loop through the values and compare msg against bodyText. If bodyText contains one of the msg's, we set a flag to true, and then perform an if statement on flag.
If you want to check anywhere in the page... then you have to do just that. Get every DOM element and check if there is your String there... I do not think there is another way.
Yes using setTimeout will do the trick for waiting before reload.
Everything works perfectly with modern browsers but for ie8 I get this error for this line:
tabValues.push(tabParams[i].split(attribute_anchor_separator));
Here the whole function:
function checkUrl()
{
if (original_url != window.location || first_url_check)
{
first_url_check = false;
url = window.location + '';
// if we need to load a specific combination
if (url.indexOf('#/') != -1)
{
// get the params to fill from a "normal" url
params = url.substring(url.indexOf('#') + 1, url.length);
tabParams = params.split('/');
tabValues = [];
if (tabParams[0] == '')
tabParams.shift();
for (var i in tabParams)
tabValues.push(tabParams[i].split(attribute_anchor_separator));
product_id = $('#product_page_product_id').val();
// fill html with values
$('.color_pick').removeClass('selected');
$('.color_pick').parent().parent().children().removeClass('selected');
count = 0;
for (var z in tabValues)
for (var a in attributesCombinations)
if (attributesCombinations[a]['group'] === decodeURIComponent(tabValues[z][0])
&& attributesCombinations[a]['attribute'] === tabValues[z][1])
{
count++;
// add class 'selected' to the selected color
$('#color_' + attributesCombinations[a]['id_attribute']).addClass('selected');
$('#color_' + attributesCombinations[a]['id_attribute']).parent().addClass('selected');
$('input:radio[value=' + attributesCombinations[a]['id_attribute'] + ']').attr('checked', true);
$('input[type=hidden][name=group_' + attributesCombinations[a]['id_attribute_group'] + ']').val(attributesCombinations[a]['id_attribute']);
$('select[name=group_' + attributesCombinations[a]['id_attribute_group'] + ']').val(attributesCombinations[a]['id_attribute']);
}
// find combination
if (count >= 0)
{
findCombination(false);
original_url = url;
return true;
}
// no combination found = removing attributes from url
else
window.location = url.substring(0, url.indexOf('#'));
}
}
return false;
}
Any ideas?? Thx!
I noticed you are using a for..in over an Array however using for..in was meant to be used for iteration over objects (not arrays):
for ( var prop in obj1 ) {
if ( obj1.hasOwnProperty(prop) ) {
// loop body goes here
}
}
What's a good way to check if a cookie exist?
Conditions:
Cookie exists if
cookie1=;cookie1=345534;
//or
cookie1=345534;cookie1=;
//or
cookie1=345534;
Cookie doesn't exist if
cookie=;
//or
<blank>
You can call the function getCookie with the name of the cookie you want, then check to see if it is = null.
function getCookie(name) {
var dc = document.cookie;
var prefix = name + "=";
var begin = dc.indexOf("; " + prefix);
if (begin == -1) {
begin = dc.indexOf(prefix);
if (begin != 0) return null;
}
else
{
begin += 2;
var end = document.cookie.indexOf(";", begin);
if (end == -1) {
end = dc.length;
}
}
// because unescape has been deprecated, replaced with decodeURI
//return unescape(dc.substring(begin + prefix.length, end));
return decodeURI(dc.substring(begin + prefix.length, end));
}
function doSomething() {
var myCookie = getCookie("MyCookie");
if (myCookie == null) {
// do cookie doesn't exist stuff;
}
else {
// do cookie exists stuff
}
}
I have crafted an alternative non-jQuery version:
document.cookie.match(/^(.*;)?\s*MyCookie\s*=\s*[^;]+(.*)?$/)
It only tests for cookie existence. A more complicated version can also return cookie value:
value_or_null = (document.cookie.match(/^(?:.*;)?\s*MyCookie\s*=\s*([^;]+)(?:.*)?$/)||[,null])[1]
Put your cookie name in in place of MyCookie.
document.cookie.indexOf('cookie_name=');
It will return -1 if that cookie does not exist.
p.s. Only drawback of it is (as mentioned in comments) that it will mistake if there is cookie set with such name: any_prefix_cookie_name
(Source)
This is an old question, but here's the approach I use ...
function getCookie(name) {
var match = document.cookie.match(RegExp('(?:^|;\\s*)' + name + '=([^;]*)'));
return match ? match[1] : null;
}
This returns null either when the cookie doesn't exist, or when it doesn't contain the requested name.
Otherwise, the value (of the requested name) is returned.
A cookie should never exist without a value -- because, in all fairness, what's the point of that? 😄
If it's no longer needed, it's best to just get rid of it all together.
function deleteCookie(name) {
document.cookie = name +"=; Path=/; Expires=Thu, 01 Jan 1970 00:00:01 GMT;";
}
ATTENTION!
the chosen answer contains a bug (Jac's answer).
if you have more than one cookie (very likely..) and the cookie you are retrieving is the first on the list, it doesn't set the variable "end" and therefore it will return the entire string of characters following the "cookieName=" within the document.cookie string!
here is a revised version of that function:
function getCookie( name ) {
var dc,
prefix,
begin,
end;
dc = document.cookie;
prefix = name + "=";
begin = dc.indexOf("; " + prefix);
end = dc.length; // default to end of the string
// found, and not in first position
if (begin !== -1) {
// exclude the "; "
begin += 2;
} else {
//see if cookie is in first position
begin = dc.indexOf(prefix);
// not found at all or found as a portion of another cookie name
if (begin === -1 || begin !== 0 ) return null;
}
// if we find a ";" somewhere after the prefix position then "end" is that position,
// otherwise it defaults to the end of the string
if (dc.indexOf(";", begin) !== -1) {
end = dc.indexOf(";", begin);
}
return decodeURI(dc.substring(begin + prefix.length, end) ).replace(/\"/g, '');
}
If you're using jQuery, you can use the jquery.cookie plugin.
Getting the value for a particular cookie is done as follows:
$.cookie('MyCookie'); // Returns the cookie value
regexObject.test( String ) is faster than string.match( RegExp ).
The MDN site describes the format for document.cookie, and has an example regex to grab a cookie (document.cookie.replace(/(?:(?:^|.*;\s*)test2\s*\=\s*([^;]*).*$)|^.*$/, "$1");). Based on that, I'd go for this:
/^(.*;)?\s*cookie1\s*=/.test(document.cookie);
The question seems to ask for a solution which returns false when the cookie is set, but empty. In that case:
/^(.*;)?\s*cookie1\s*=\s*[^;]/.test(document.cookie);
Tests
function cookieExists(input) {return /^(.*;)?\s*cookie1\s*=/.test(input);}
function cookieExistsAndNotBlank(input) {return /^(.*;)?\s*cookie1\s*=\s*[^;]/.test(input);}
var testCases = ['cookie1=;cookie1=345534;', 'cookie1=345534;cookie1=;', 'cookie1=345534;', ' cookie1 = 345534; ', 'cookie1=;', 'cookie123=345534;', 'cookie=345534;', ''];
console.table(testCases.map(function(s){return {'Test String': s, 'cookieExists': cookieExists(s), 'cookieExistsAndNotBlank': cookieExistsAndNotBlank(s)}}));
Note that if a cookie is secure, you cannot check in client side for its existence using document.cookie (which all of the answers are using). Such cookie can be checked only at sever side.
instead of the cookie variable you would just use document.cookie.split...
var cookie = 'cookie1=s; cookie1=; cookie2=test';
var cookies = cookie.split('; ');
cookies.forEach(function(c){
if(c.match(/cookie1=.+/))
console.log(true);
});
There are several good answers here. I however prefer [1] not using a regular expression, and [2] using logic that is simple to read, and [3] to have a short function that [4] does not return true if the name is a substring of another cookie name . Lastly [5] we can't use a for each loop since a return doesn't break it.
function cookieExists(name) {
var cks = document.cookie.split(';');
for(i = 0; i < cks.length; i++)
if (cks[i].split('=')[0].trim() == name) return true;
}
function getCookie(name) {
var dc = document.cookie;
var prefix = name + "=";
var begin = dc.indexOf("; " + prefix);
if (begin == -1) {
begin = dc.indexOf(prefix);
if (begin != 0) return null;
else{
var oneCookie = dc.indexOf(';', begin);
if(oneCookie == -1){
var end = dc.length;
}else{
var end = oneCookie;
}
return dc.substring(begin, end).replace(prefix,'');
}
}
else
{
begin += 2;
var end = document.cookie.indexOf(";", begin);
if (end == -1) {
end = dc.length;
}
var fixed = dc.substring(begin, end).replace(prefix,'');
}
// return decodeURI(dc.substring(begin + prefix.length, end));
return fixed;
}
Tried #jac function, got some trouble, here's how I edited his function.
For anyone using Node, I found a nice and simple solution with ES6 imports and the cookie module!
First install the cookie module (and save as a dependency):
npm install --save cookie
Then import and use:
import cookie from 'cookie';
let parsed = cookie.parse(document.cookie);
if('cookie1' in parsed)
console.log(parsed.cookie1);
Using Javascript:
function getCookie(name) {
let matches = document.cookie.match(new RegExp(
"(?:^|; )" + name.replace(/([\.$?*|{}\(\)\[\]\\\/\+^])/g, '\\$1') + "=([^;]*)"
));
return matches ? decodeURIComponent(matches[1]) : undefined;
}
Parse cookies with Array.prototype.reduce() into an object (ES6)
const cookies = document.cookie.split(";").reduce((e, t) => {
const [c, n] = t.trim().split("=").map(decodeURIComponent);
try { // this can be removed if you do not need JSON cookies parsed
return Object.assign(e, {
[c]: JSON.parse(n)
})
}
catch (t) {
return Object.assign(e, {
[c]: n
})
}
}, {})
Check if your cookie is there
typeof cookies.yourCookie === "string";
If anyone is still looking into this post maybe this will help.
First do a function to get the cookie, something like this..
function getCookie(cname) {
let name = cname + "=";
let ca = document.cookie.split(';');
for(let i = 0; i < ca.length; i++) {
let c = ca[i];
while (c.charAt(0) == ' ') {
c = c.substring(1);
}
if (c.indexOf(name) == 0) {
return c.substring(name.length, c.length);
}
}
return "";
}
Then you could check if the specific cookie exists before doing something else
if( getCookie(mycookieName)){
// do something....
}
// check if cookie is present
function is_CookiePresent( cookieName ){
if( void 0 != cookieName && "" != cookieName && null != cookieName ){
var is_present = document.cookie.split(";").filter(e=>{
if(e.trim().split("=").includes(cookieName)) return true;
})
if(!is_present.length){return false;}
return true;
}
else{
return false;
}
}
// Get cookie name value :)
function getCookieValue( cookieName ){
if( void 0 != cookieName && "" != cookieName && null != cookieName ){
var is_present = document.cookie.split(";").filter(e=>{
if(e.trim().split("=").includes(cookieName)) return true;
})
if(!is_present.length){return false;}
var __CookieValue = is_present.join('').trim();
return __CookieValue.substring(__CookieValue.indexOf('=')+1);
}
else{
return false;
}
}
use this method instead:
function getCookie(name) {
var value = "; " + document.cookie;
var parts = value.split("; " + name + "=");
if (parts.length == 2) return parts.pop().split(";").shift();
else return null;
}
function doSomething() {
var myCookie = getCookie("MyCookie");
if (myCookie == null) {
// do cookie doesn't exist stuff;
}
else {
// do cookie exists stuff
}
}
/// ************************************************ cookie_exists
/// global entry point, export to global namespace
/// <synopsis>
/// cookie_exists ( name );
///
/// <summary>
/// determines if a cookie with name exists
///
/// <param name="name">
/// string containing the name of the cookie to test for
// existence
///
/// <returns>
/// true, if the cookie exists; otherwise, false
///
/// <example>
/// if ( cookie_exists ( name ) );
/// {
/// // do something with the existing cookie
/// }
/// else
/// {
/// // cookies does not exist, do something else
/// }
function cookie_exists ( name )
{
var exists = false;
if ( document.cookie )
{
if ( document.cookie.length > 0 )
{
// trim name
if ( ( name = name.replace ( /^\s*/, "" ).length > 0 ) )
{
var cookies = document.cookie.split ( ";" );
var name_with_equal = name + "=";
for ( var i = 0; ( i < cookies.length ); i++ )
{
// trim cookie
var cookie = cookies [ i ].replace ( /^\s*/, "" );
if ( cookie.indexOf ( name_with_equal ) === 0 )
{
exists = true;
break;
}
}
}
}
}
return ( exists );
} // cookie_exists
function getcookie(name = '') {
let cookies = document.cookie;
let cookiestore = {};
cookies = cookies.split(";");
if (cookies[0] == "" && cookies[0][0] == undefined) {
return undefined;
}
cookies.forEach(function(cookie) {
cookie = cookie.split(/=(.+)/);
if (cookie[0].substr(0, 1) == ' ') {
cookie[0] = cookie[0].substr(1);
}
cookiestore[cookie[0]] = cookie[1];
});
return (name !== '' ? cookiestore[name] : cookiestore);
}
To get a object of cookies simply call getCookie()
To check if a cookie exists, do it like this:
if (!getcookie('myCookie')) {
console.log('myCookie does not exist.');
} else {
console.log('myCookie value is ' + getcookie('myCookie'));
}
Or just use a ternary operator.
function hasCookie(cookieName){
return document.cookie.split(';')
.map(entry => entry.split('='))
.some(([name, value]) => (name.trim() === cookieName) && !!value);
}
Note: The author wanted the function to return false if the cookie is empty i.e. cookie=; this is achieved with the && !!value condition. Remove it if you consider an empty cookie is still an existing cookie…
var cookie = 'cookie1=s; cookie1=; cookie2=test';
var cookies = cookie.split('; ');
cookies.forEach(function(c){
if(c.match(/cookie1=.+/))
console.log(true);
});
You can verify if a cookie exists and it has a defined value:
function getCookie(cookiename) {
if (typeof(cookiename) == 'string' && cookiename != '') {
const COOKIES = document.cookie.split(';');
for (i = 0; i < COOKIES.length; i++) {
if (COOKIES[i].trim().startsWith(cookiename)) {
return COOKIES[i].split('=')[1];
}
}
}
return null;
}
const COOKIE_EXAMPLE = getCookie('example');
if (COOKIE_EXAMPLE == 'stackoverflow') { ... }
// If is set a cookie named "example" with value "stackoverflow"
if (COOKIE_EXAMPLE != null) { ... }
// If is set a cookie named "example" ignoring the value
It will return null if cookie doesn't exists.