Question: I am making a CRUD list item Page.

When I add or edit list item, I want to load those page as a Modal popup.

For now I just use redirect and move to another page.

And I heard that use SP.UI.ModalDialog option, but I don`t know how to use it.

My Code is below, Please somebody help me.

```
protected void lnkbtnAdd_Click(object sender, EventArgs e)
{
   string siteUrl = SPContext.Current.Web.Url;
   string listBaseUrl = ddlList.SelectedItem.Text;
   string listUrl = listBaseUrl.Replace("/sites/dev/", "");

   Response.Redirect(string.Format(siteUrl + "/_layouts/15/ListItemControl/AddNewItem.aspx?parm={0}", listUrl));
}

```

Answer: 
```
 function openDialog(pageURL, aTitle, callback) 
{
        if (callback == null || typeof callback == 'undefined')
            callback = callbackOpenDialog;
        //Create dialog options
        var diagOptions = {
            url: itemPath,
            title: aTitle,
            allowMaximize: true,
            showClose: true,
            height: 500,
            dialogReturnValueCallback: callback
        };
        //Show Dialog
        SP.UI.ModalDialog.showModalDialog(diagOptions);

    }

```

In above function you need to pass pageURL and title whatever you want to display.
Please make sure that sp.js load before this function run.
You can use OOTB function 

```
OpenPopUpPage('dialog url here', function(sts,data) { 
 // sts could be 0(if closed or clicked cancel on the dialog box) or 1(if you click save or OK)
 //data contains data returned from popup
 //code you want to execute after you close dialog. if not required replace this function with null
},width,height);

```