give Focus() or click() in a webview text field C#

Question

I am developing a webbrowser in UWP(windows universal application) using the C#language, to assign value to a text field that is in webview I used the following script:

string functionString = String.Format("document.getElementById('chatMessageSend').innerText = '{0}';", textbox.Text);
await Webview_uol.InvokeScriptAsync("eval", new string[] { functionString });

On the HTML page what I have is this:

<div id="chatMessageSend" data-joyride="data-joyride" ng-model="text" name="text" bp-textarea="bp-textarea" contenteditable="true" tabindex="1" class="ng-valid ng-dirty"></div>

But how the site uses NG-click() If I’m not mistaken, I can’t give focus() or even click() in the text field. The field only validates to click if in fact I use the mouse, via code is not working, someone can help me with this?

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The site is Uol chat, in particular this room: https://batepapo.uol.com.br/beta/Cidades-e-regi%C3%B5es/Cear%C3%A1/L/Limoeiro-do-Norte/Limoeiro-do-Norte-(2) after entering it my program has to send a message to the chat room, I can fill the field and until you click the button, but the message will not because you need some kind of validation that I have not been able to do yet...