Read and write cookies from javascript. Small and simple.

cookie.js

// cookie.js
//
// Usage:
//    $.cookie('mine', 'data', 5*60*1000)  -- write data to cookie named mine that lasts for five minutes
//    $.cookie('mine')                     -- read the cookie that was just set, function result will be 'data'
//    $.cookie('mine', '', -1)             -- delete the cookie

$.cookie = function(name,value,ms) {
    if(arguments.length < 2) {
        // read cookie
        var cookies = document.cookie.split(';')
        for(var i=0; i < cookies.length; i++) {
            var c = cookies[i].replace(/^\s+/, '')
            if(c.indexOf(name+'=') == 0) {
                return decodeURIComponent(c.substring(name.length+1).split('+').join(' '))    
            }
        }
        return null
    }

    // write cookie
    var date = new Date()
    date.setTime(date.getTime()+ms)
    document.cookie = name+"=" + encodeURIComponent(value) + (ms ? ";expires="+date.toGMTString() : '') + ";path=/"
}

notes.md

To write JSON: $.cookie('name', JSON.stringify('data'))
And to read: $.parseJSON($.cookie('name'))

UTF8 characters cause some browsers to truncate the cookie string. Really irritating. Encoding in Base64 using http://code.google.com/p/javascriptbase64/ seems to fix it 100%.