Textarea and button, how to link?

Question

css

Hello! I made such nonsense and the question arose for me, how to associate buttons with a textarea, when a button is clicked, a certain letter appears in the textarea? I think that I need to use the onclick event, but I don't know how to apply

<div id="kboard">
    <div id="firstrow"> 
      <button>по</button>
      <button>во</button>
      <button>апа</button>
    </div>
    <div id="secondrow">
      <button>q</button>
      <button>w</button>
      <button>e</button>
      <button>r</button>
      <button>t</button>
      <button>y</button>
      <button>u</button>
      <button>i</button>
      <button>o</button>
      <button>p</button>
    </div>
    <div id="thirdrow">
      <button>a</button>
      <button>s</button>
      <button>d</button>
      <button>f</button>
      <button>g</button>
      <button>h</button>
      <button>j</button>
      <button>k</button>
      <button>l</button>
    </div>
    <div id="fourthrow">
      <button><img src="img\up.png"></button>
      <button>z</button>
      <button>x</button>
      <button>c</button>
      <button>v</button>
      <button>b</button>
      <button>n</button>
      <button>m</button>
      <button><img src="img\left.png"></button>
    </div>
    <div id="fifthrow">
      <button>123</button>
      <button><img src="img\globus.png"></button>
      <button>space</button>
      <button>.</button>
      <button><img src="img\enter.png"></button>
    </div>
  </div>

Answer 1

Smells like bullshit...

$("#kboard").on("click", "button", function(){
  var Tc = this.textContent;
  if(Tc.length===1) $("textarea").get(0).value += Tc;
});