How do I check if a cookie exists

Question

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  lt blank gt

User · Answer

function hasCookie cookieName   return document cookie split       map entry   gt  entry split        some   name  value     gt   name trim       cookieName   amp  amp    value      Note  The author wanted the function to return false if the cookie is empty i e  cookie   this is achieved with the  amp  amp    value condition  Remove it if you consider an empty cookie is still an existing cookie

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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

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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

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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

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instead of the cookie variable you would just use document cookie split      x000D   x000D  var cookie    cookie1 s  cookie1   cookie2 test   x000D  var cookies   cookie split        x000D  cookies forEach function c   x000D    if c match  cookie1       x000D     console log true   x000D      x000D   x000D   x000D

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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

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function getcookie name             let cookies   document cookie      let cookiestore                cookies   cookies split  quot   quot             if  cookies 0      quot  quot   amp  amp  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

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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   quot    Path    Expires Thu  01 Jan 1970 00 00 01 GMT  quot

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cookie exists      global entry point  export to global namespace       lt synopsis gt        cookie exists   name             lt summary gt        determines if a cookie with name exists          lt param name  name  gt        string containing the name of the cookie to test for        existence          lt returns gt        true  if the cookie exists  otherwise  false          lt example gt        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  gt  0                                                  trim name       if     name   name replace      s         length  gt  0                       var cookies   document cookie split                  var name with equal   name                 for   var i   0    i  lt  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

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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

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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

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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

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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

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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

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Using Javascript    function getCookie name          let matches   document cookie match new RegExp                       name replace                              g      1                                return matches   decodeURIComponent matches 1     undefined

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x000D   x000D  var cookie    cookie1 s  cookie1   cookie2 test   var cookies   cookie split        cookies forEach function c     if c match  cookie1          console log true       x000D   x000D   x000D

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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

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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  lt  cks length  i        if  cks i  split      0  trim      name  return true

[javascript] How do I check if a cookie exists?

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