Html button code is as follows, I tried a simple onclick function on the button and an event on the second button

<button onclick="myFunction()">Click me</button>
<button id="button">Paste</button>

Javascript code is as follows

function myFunction() {

      var clipboarddata =  window.event.clipboardData.getData('text');    
      console.log("paste value" + clipboarddata);
}

var button = document.getElementById("button");
button.addEventListener("click", function(event){
   alert(event.target);
   event.preventDefault();
   var clipboarddata =  window.event.clipboardData.getData('text');    
   console.log("paste value" + clipboarddata);
});

I get the same error both ways