in salesforce/canvas/public/javascripts/canvas-all.js [600:617]
function set(name, value, days) {
var expires = '',
date;
if (days) {
date = new Date();
date.setTime(date.getTime() + days * 24 * 60 * 60 * 1e3);
expires = '; expires=' + date.toGMTString();
} else {
expires = '';
}
document.cookie =
name +
'=' +
value +
expires +
'; path=/' +
(isSecure() === true ? '; secure' : '');
}