What is the “best” way to get and set a single cookie value using JavaScript

by

Stolen from http://www.quirksmode.org/js/cookies.html#script

function createCookie(name,value,days) {
    if (days) {
        var date = new Date();
        date.setTime(date.getTime()+(days*24*60*60*1000));
        var expires = "; expires="+date.toUTCString();
    }
    else var expires = "";
    document.cookie = name+"="+value+expires+"; path=/";
}

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 eraseCookie(name) {
    createCookie(name,"",-1);
}

using it:

var oldCount = parseInt(readCookie('hitCount'), 10) || 0;
createCookie('hitCount', oldCount + 1, 7);

as pointed out in the comments, you should cast to an int since cookies are stored and returned as strings. Using foo++ or ++foo will actually cast for you, but it’s safer to know exactly what you’re working with:

var x = "5";  // x = "5" (string)
x += 1;       // x = "51" (string!)
x += 5;       // x = "515" (string!)
++x;          // x = 516 (number)

More Related Contents:

  1. How do you increment a cookie value?
  2. How to delete a cookie?
  3. Get cookie by name
  4. Clearing all cookies with JavaScript
  5. How to set a cookie for another domain
  6. What is the shortest function for reading a cookie by name in JavaScript?
  7. Javascript getCookie functions
  8. Setting cross-domain cookies in Safari
  9. What are cookies and sessions, and how do they relate to each other?
  10. How do I check if a cookie exists?
  11. SameSite warning Chrome 77
  12. How do I create and read a value from cookie with javascript?
  13. Javascript Cookie with no expiration date
  14. How to expire a cookie in 30 minutes using jQuery?
  15. can i be notified of cookie changes in client side javascript
  16. jQuery $.cookie is not a function
  17. Pure Javascript – store object in cookie
  18. Why doesn’t document.cookie show all the cookie for the site?
  19. CORS cookie credentials from mobile WebView loaded locally with file://
  20. Javascript document.cookie always returns empty string
  21. How can I handle browser tab close event in Angular? Only close, not refresh
  22. How to use cookie inside `getServerSideProps` method in Next.js?
  23. Best way to store small UI user preferences in web app? [closed]
  24. How do I edit PHP variable with JavaScript/jQuery?
  25. Cookies Only set in Chrome – not set in Safari, Mobile Chrome, or Mobile Safari
  26. Set-Cookie in HTTP header is ignored with AngularJS
  27. Why cookies and set-cookie headers can’t be set while making xmlhttprequest using setRequestHeader?
  28. Getting setting cookies on different domains, with JavaScript or other
  29. How to modify Cookie from Ajax call
  30. How to update and delete a cookie?

Leave a Comment