<!DOCTYPE html> <html> <body> <h1>JavaScript 数字</h1> <p>超大或超小的数可通过科学（指数）计数法来写：</p> <p id="demo"></p> <script> var x = 123e5; var y = 123e-5; document.getElementById("demo").innerHTML = x + "<br>" + y; </script> </body> </html>
