​x
 
<!DOCTYPE html>
<html>
<body>
​
<p>单击该按钮可显示不同数字的平方根。</p>
​
<button onclick="myFunction()">试一试</button>
​
<p id="demo"></p>
​
<script>
function myFunction() {
  var a = Math.sqrt(0);
  var b = Math.sqrt(1);
  var c = Math.sqrt(9);
  var d = Math.sqrt(64);
  var e = Math.sqrt(-9);
​
  var x = a + "<br>" + b + "<br>" + c + "<br>" + d + "<br>" + e;
  document.getElementById("demo").innerHTML = x;
}
</script>
​
</body>
</html>
​