Read a javascript cookie by name

Question

I have set a cookie using  document cookie         MYBIGCOOKIE     value           expires     now toGMTString             path       Now there are between 5 and 10 cookies set on this site  is there a way to check the value ofthis cookie by name   if  document cookie MYBIGCOOKIE     1         alert  it is 1

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Use the RegExp constructor and multiple replacements to clarify the syntax   function getCook cookiename            Get name followed by anything except a semicolon   var cookiestring RegExp cookiename           exec document cookie        Return everything after the equal sign  or an empty string if the cookie name not found   return decodeURIComponent   cookiestring   cookiestring toString   replace                             Sample usage var cookieValue   getCook  MYBIGCOOKIE

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The point of Stack Overflow is to provide a database of good quality answers  so I am going to reference some standard source code and an article that gives examples   http   www codelib net javascript cookies html  Note  The code is regular-expression free for greatly enhanced efficiency   Using the source code provided  you would use cookies like this   makeCookie  color    silver      This saves a cookie indicating that the color is silver  The cookie would expire after the current session  as soon as the user quits the browser    makeCookie  color    green     domain   gardens home com        This saves the color green for gardens home com   makeCookie  color    white     domain    home com   path    invoices      makeCookie  invoiceno    0259876     path    invoices   secure  true       saves the color white for invoices viewed anywhere at home com  The second cookie is a secure cookie  and records an invoice number  This cookie will be sent only to pages that are viewed through secure HTTPS connections  and scripts within secure pages are the only scripts allowed to access the cookie   One HTTP host is not allowed to store or read cookies for another HTTP host  Thus  a cookie domain must be stored with at least two periods  By default  the domain is the same as the domain of the web address which created the cookie   The path of an HTTP cookie restricts it to certain files on the HTTP host  Some browsers use a default path of    so the cookie will be available on the whole host  Other browsers use the whole filename  In this case  if  invoices overdue cgi creates a cookie  only  invoices overdue cgi is going to get the cookie back   When setting paths and other parameters  they are usually based on data obtained from variables like location href  etc  These strings are already escaped  so when the cookie is created  the cookie function does not escape these values again  Only the name and value of the cookie are escaped  so we can conveniently use arbitrary names or values  Some browsers limit the total size of a cookie  or the total number of cookies which one domain is allowed to keep   makeCookie  rememberemail    yes     expires  7     makeCookie  rememberlogin    yes     expires  1     makeCookie  allowentergrades    yes     expires  1 24       these cookies would remember the user s email for 7 days  the user s login for 1 day  and allow the user to enter grades without a password for 1 hour  a twenty-fourth of a day   These time limits are obeyed even if they quit the browser  and even if they don t quit the browser  Users are free to use a different browser program  or to delete cookies  If they do this  the cookies will have no effect  regardless of the expiration date   makeCookie  rememberlogin    yes     expires  -1       deletes the cookie  The cookie value is superfluous  and the return value false means that deletion was successful   A expiration of -1 is used instead of 0  If we had used 0  the cookie might be undeleted until one second past the current time  In this case we would think that deletion was unsuccessful    Obviously  since a cookie can be deleted in this way  a new cookie will also overwrite any value of an old cookie which has the same name  including the expiration date  etc  However  cookies for completely non-overlapping paths or domains are stored separately  and the same names do not interfere with each other  But in general  any path or domain which has access to a cookie can overwrite the cookie  no matter whether or not it changes the path or domain of the new cookie   rmCookie  rememberlogin      also deletes the cookie  by doing makeCookie  rememberlogin         expires  -1     This makes the cookie code longer  but saves code for people who use it  which one might think saves more code in the long run

User · Answer

using jquery-cookie  I find this library helpful  3 128 kb of pure convenience   add script   lt script src   path to jquery cookie js  gt  lt  script gt    set cookie    cookie  name    value      read cookie    cookie  name

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Here is an example implementation  which would make  this process seamless  Borrowed from AngularJs   var CookieReader    function    var lastCookies       var lastCookieString        function safeGetCookie         try           return document cookie              catch  e            return              function safeDecodeURIComponent str        try           return decodeURIComponent str         catch  e            return str           function isUndefined value        return typeof value      undefined      return function          var cookieArray  cookie  i  index  name      var currentCookieString   safeGetCookie         if  currentCookieString     lastCookieString            lastCookieString   currentCookieString          cookieArray   lastCookieString split                lastCookies                for  i   0  i  lt  cookieArray length  i                  cookie   cookieArray i               index   cookie indexOf                   if  index  gt  0      ignore nameless cookies                 name   safeDecodeURIComponent cookie substring 0  index                     if  isUndefined lastCookies name                          lastCookies name    safeDecodeURIComponent cookie substring index   1                                                        return lastCookies

User · Answer

One of the shortest ways is this  however as mentioned previously it can return the wrong cookie if there s similar names  MyCookie vs AnotherMyCookie    var regex    MyCookie          ig  var match   regex exec document cookie   var value   match 1     I use this in a chrome extension so I know the name I m setting  and I can make sure there won t be a duplicate  more or less

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Unfortunately  Javascript s cookie syntax is nowhere near as nice as that   In fact  in my opinion  it s one of the worst designed parts   When you try to read document cookie  you get a string containing all the cookies set   You have to parse the string  separating by the semicolon   character   Rather than writing this yourself  there are plenty of versions available on the web   My favourite is the one at quirksmode org   This gives you createCookie  readCookie and deleteCookie functions

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The simplest way to read a cookie I can think is using Regexp like this     Replace COOKIE NAME with the name of your cookie   document cookie match  COOKIE NAME            1    How does it work   Cookies are stored in document cookie like this  cookieName cookieValue cookieName2 cookieValue2        The regex searches the whole cookie string for literaly  COOKIE NAME   and captures anything after it that is not a semicolon until it actually finds a semicolon   Then we use  1  to get the second item from array  which is the captured group

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Here is an API which was written to smooth over the nasty browser cookie  API    http   code google com p cookies

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You can use the following function   function getCookiesMap cookiesString      return cookiesString split           map function cookieString            return cookieString trim   split                   reduce function acc  curr            acc curr 0     curr 1           return acc                  When  called with document cookie as parameter  it will return an object  with the cookies keys as keys and the cookies values   var cookies   getCookiesMap document cookie   var cookieValue   cookies  MYBIGCOOKIE

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function getCookie c name        var i x y ARRcookies document cookie split            for  i 0 i lt ARRcookies length i                  x ARRcookies i  substr 0 ARRcookies i  indexOf                y ARRcookies i  substr ARRcookies i  indexOf      1           x x replace    s   s   g              if  x  c name                        return unescape y                        Source  W3Schools  Edit  as  zcrar70 noted  the above code is incorrect  please see the following answer Javascript getCookie functions

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document cookie  MYBIGCOOKIE 1     Your cookies would look like    MYBIGCOOKIE 1  PHPSESSID d76f00dvgrtea8f917f50db8c31cce9    first of all read all cookies   var read cookies   document cookie    then split all cookies with       var split read cookie   read cookies split         then use for loop to read each value  Into loop each value split again with       for  i 0 i lt split read cookie length i         var value split read cookie i       value value split           if value 0    MYBIGCOOKIE   amp  amp  value 1    1            alert  it is 1

[javascript] Read a javascript cookie by name

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