Unable to get property 'showmodaldialog' of undefined or null reference

Question

I got "unable to get property 'showmodaldialog' of undefined or null reference" error when I try to open the list displayform in SharePoint 2013 modal dialog.

This is my script code:

<script type="text/javascript">
        function openDialog( pUrl ) {  
         SP.UI.ModalDialog.showModalDialog(   
         {  
          url: pUrl,
         width: 650,  
         height:600,  
         title: "MyTitle"
          }  
         );  
    }  
</script>

Calling:

<a href="javascript:openDialog('../../News/Lists/Posts/Post.aspx?ID={@ows_ID}')"><xsl:value-of select="@ows_LinkTitle"/></a>

Could anyone help me to resolve this issue?

Answer 1

This is happening because SP.UI.Dialog.js file is not loaded. Modify your code as below

<script type="text/javascript">
    function openDialog( pUrl ) {  
        var options = {
            url: pUrl,
            width: 650,  
            height:600,  
            title: "MyTitle"
        };
        SP.SOD.execute('sp.ui.dialog.js', 'SP.UI.ModalDialog.showModalDialog', options);
    }  
</script>