Calling code behind method from javascript?

Question

I have method in code behind:

protected void myMethod()
    {
        Literal1.Text = System.DateTime.Now.ToString();
    }

I need to call this method every second. I found that i should use javascipt, here's my scipt:

<script>
   function test() {
      // ???
   }
   setInterval(test, 1000);
</script>

but i don't know how to call myMethod from javascript?

I think your example is too simplified. If you let us know what you are calling every second and why we can provide better answers specific to your situation. — Doug Wilson
– Doug Wilson, Commented Apr 29, 2013 at 18:45
@Hellfire I think he just wants to know in general how to get from client to server. — Yatrix
– Yatrix, Commented Apr 30, 2013 at 13:45
I edited my question to pull the examples from the links I provided. Have a look. — Yatrix
– Yatrix, Commented Apr 30, 2013 at 13:51

AContractor · Accepted Answer · 2013-04-29 17:59:20Z

1

If you want to avoid the server round-trip, which you might because of network delay, you can use javascript like so

var now = new Date();
dateFormat(now, "dddd, mmmm dS, yyyy, h:MM:ss TT");// Saturday, June 9th, 2007, 5:46:21 PM

Check out http://blog.stevenlevithan.com/archives/date-time-format to see what other type of date formats are possible.

edited Apr 29, 2013 at 17:59

answered Apr 29, 2013 at 17:07

AContractor

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2 Comments

user2061066 Over a year ago

round-trip, hmm, you're right, it was just an example, in my site i have endDate in database and i need to get this endDate from database and then show dynamically how much time left (endDate - System.DateTime.Now). How can i do that?

AContractor Over a year ago

Hmm ok. If your storing time values in the database then checking on the server is probably better. Doing everything on the client side introduces issues like dealing with timezones,etc which can get complicated if you need to compare your own time value. Using AJAX would be your best bet. I would suggesr instead of showing the exact time left do something like '2 mins remainng' , 'less than 30 secs' etc so you don't need to 100% accurate time.

Yatrix · Accepted Answer · 2013-04-30 13:51:08Z

Use AJAX. https://developer.mozilla.org/en-US/docs/AJAX/Getting_Started This will allow you to call a designated server-side method from the client.

From the link above:

function makeRequest(url) {
    if (window.XMLHttpRequest) { // Mozilla, Safari, ...
      httpRequest = new XMLHttpRequest();
    } else if (window.ActiveXObject) { // IE
      try {
        httpRequest = new ActiveXObject("Msxml2.XMLHTTP");
      } 
      catch (e) {
        try {
          httpRequest = new ActiveXObject("Microsoft.XMLHTTP");
        } 
        catch (e) {}
      }
    }

    if (!httpRequest) {
      alert('Giving up :( Cannot create an XMLHTTP instance');
      return false;
    }
    httpRequest.onreadystatechange = alertContents;
    httpRequest.open('GET', url);
    httpRequest.send();
  }

  function alertContents() {
    if (httpRequest.readyState === 4) {
      if (httpRequest.status === 200) {
        alert(httpRequest.responseText);
      } else {
        alert('There was a problem with the request.');
      }
    }
  }
})();

You'll have to decorate your server-side method with the [WebMethod] attribute and declare it as public and static. http://msdn.microsoft.com/en-us/library/byxd99hx(v=vs.90).aspx

From MSDN:

[System.Web.Services.WebMethod(EnableSession=true)]
public int GetNumberOfConversions()
{
   return (int) Session["Conversions"];
}

It's that easy.

I have to question calling a method from client to server every second, however. You can handle that date business in JavaScript alone. Making a round-trip is not going to work out well for you, I'm betting.

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