How to describe the action click button in webview


Hello for all
in my app, i use webview tag to load URL.

   " <webview id="wv1" src="" "></webview> "

   in webpage have a button :  "  <button id="btn1"> click </button>  "

i want to describe the action ‘click’ for this button:

" var wv=document.querySelector('#wv1');
    wv.executeJavaScript('document.querySelector("#btn1").click()'); "

but it don’t work.
please help me ,how to do it.
thank you!