StartGames,
<!DOCTYPE HTML>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
</head>
<body>
12345
<div>Вставить</div>
<input type="text" value="" id="info">
<script>
let text = '';
document.addEventListener('selectionchange', function()
{
if(getSelection().toString().length) text = getSelection().toString();
}, false
);
document.querySelector('div').addEventListener('click', function()
{
info.value = text;
}, false
)
</script>
</body>
</html>