点击运行
<!DOCTYPE html> <html> <body> <p>函数可以访问函数内定义的变量：</p> <button type="button" onclick="myFunction()">单击这里！</button> <p id="demo"></p> <script> function myFunction() { var a = 4; document.getElementById("demo").innerHTML = a * a; } </script> </body> </html>
运行结果
