我每天如何在javascript中加载一次运行函数？

Question

Let's say it's June 18 and a person runs the javascript and it runs a function on load but it doesn't run the function later that day even if the person closes the window or program in my case. However, on June 19 if the person opens the program and it runs the javascript then it runs the function because it's a new day and hasn't run that day yet... So basically, how do I make an onload function only work once per a day? It has to be javascript because the program I'm using can only be assisted by javascript files and nothing else. The person has to download the files to their computer so how would I go about saving and retrieving the localStorage?

Answer 1

You can use localStorage to achieve this. Sample Code:

/* returns null if local storage is not defined */
var localVal = localStorage.getItem('someUniqueName'); 

if(localVal  == null){ 
    // execute the function
}else{
    var tempd = new Date();
    var str = tempd.getDay() + tempd.getMonth() + tempd.getFullYear();
    if(localVal.localeCompare(str) == -1){
        //execute function
        localStorage.setItem('someUniqueName',str);
    }
}

If you wish to create a cookie and handle it, then you may go through this question

Answer 2

You can create a cookie on the user's browser that persists till the end of the day. If you are using jQuery, you can do as follows ( taken from here ):

var currentDate = new Date();
expirationDate = new Date(currentDate.getFullYear(), currentDate.getMonth(), currentDate.getDate()+1, 0, 0, 0);
$.cookie("ultOS", "5", {expires: expirationDate});

If you are using plain javascript, then the way to do this would be as follows (from here ):

  function createCookie(name,value,date) {
        if (date) {
            var expires = "; expires="+date.toGMTString();
        }
        else var expires = "";
        document.cookie = name+"="+value+expires+"; path=/";
    }

var today = Date();
var midnight = today.getDate()+1
midnight.setHours(0,0,0,0);
createCookie("Valid","true",midnight);

At the beginning of every page load, just check the value of this cookie.