How to change the value of a variable once per day in Java/javascript

Question

I'm trying to make an application/script for my school which displays the day's schedule. The catch with this is that my school runs on an 8 day cycle, so that complicates things. I have aa variable called cycleDay , but how would I go about updating this just once per day, and not more than that? If there's another way you can think of doing this, please let me know.

Thanks!

Answer 1

Use Date and document.cookies to update your variable. Also i used two utility methods to manipulate document.cookies

var today = parseInt(new Date().getTime()/(1000*3600*24))

var cookies = getCookies();

if(cookies["last_updated"] && cookies["last_updated"]<today) 
{
    /* update variable */
    setCookie("last_updated", today, 1);

}

/* utility methods starts, adding utility methods to simplify setting and getting    cookies  */
function setCookie(name, value, daysToLive) {
   var cookie = name + "=" + encodeURIComponent(value);
   if (typeof daysToLive === "number")
      cookie += "; max-age=" + (daysToLive*60*60*24);
   document.cookie = cookie;
 }

function getCookies() {
    var cookies = {}; // The object we will return
    var all = document.cookie; // Get all cookies in one big string
    if (all === "") // If the property is the empty string
       return cookies; // return an empty object
    var list = all.split("; "); // Split into individual name=value pairs
    for(var i = 0; i < list.length; i++) { // For each cookie
       var cookie = list[i];
       var p = cookie.indexOf("="); // Find the first = sign
       var name = cookie.substring(0,p); // Get cookie name
       var value = cookie.substring(p+1); // Get cookie value
       value = decodeURIComponent(value); // Decode the value
       cookies[name] = value; // Store name and value in object
  }
  return cookies;
}
/* utility methods ends */

Answer 2

private Date lastUpdate = now()-1;
private myDailyChahgedValue;

Integer getMyDailyChangedValue() {
 if (lastUpdate <> now()) {
  myDailyChahgedValue ++;
}

return value;

}

Please note it is an a draft of code what shows main idea

Answer 3

You can use, say, the getTime() function of the Date object, which returns the current time in milliseconds after January 1, 1970 (source: http://www.w3schools.com/jsref/jsref_gettime.asp ), and save that value (eg in var lastUpdateTime ). Then periodically check if the difference between the current time and that saved time is more than a day. If so, update cycleDay , and also update lastUpdateTime to the time when you updated.

For instance, initialize with:

var lastUpdateTime = new Date().getTime();

Somewhere else in your code:

var currentTime = new Date().getTime();
if(currentTime - lastUpdateTime >= 24*60*60*1000) // number of milliseconds in a day
{
    // update cycleDay
    lastUpdateTime = currentTime;
    // ...
}