Question

I want to increment a cookie value every time a page is referenced even if the page is loaded from cache. What is the ‘best’ or most concise way to implement this?

Answer 1

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)