javascript - Document.getElementById('Button').click(); not triggering Code-Behind -

i'm new coding javascript/vb.net , i'm having trouble making button2 onclick event fire.

code-behind click event button1 in page.aspx.vb

protected sub _lnbcomments_click(byval sender object, byval e system.eventargs)            //some code needs run before opening modal page            dim script string = "javascriptcode();"            scriptmanager.registerstartupscript(me.upntoolbar, me.upntoolbar.gettype(), "commentsclick", script, true) end sub 

js file

function showmodal(page,name,style){     var r = window.showmodaldialog(page,window,style); } function javascriptcode(){     var jsbutton = document.getelementbyid('ct100_sitecontent__hiddenbtncomments'); //i made sure clientid correct     jsbutton.click() //this should trigger onclick event , open modalpage } 

page onload of page.aspx

me._hiddenbtncomments.attributes.add("onclick","showmodal('somepage.aspx','somepage','somestyle')") 

the problem javascript code being fired , modal page opened. however, after closing modal page, code-behind click event not triggered. ideas what's wrong code?

page.aspx button 2 mark-up

<asp:button id="_hiddenbtncomments" runat="server" style="display:none" onclick="_hiddenbtncomments_click"></asp:button> 

code-behind click event button2 in page.aspx.vb

protected sub _hiddenbtncomments_click(byval sender object, byval e system.eventargs) handles _hiddenbtncomments.click //some code needs run after modal page closes. end sub 

edit: friend of mine suggested using window.open instead of window.showmodaldialog() , code-behind click event being triggered! however, need use window.showmodaldialog since users expecting,

click() doesn't fire click event in javascript. use jquery or use dispatchevent see post: how simulate click javascript?