<!DOCTYPE html> <html> <body> <h2>JavaScript 数字</h2> <p>调用 myMethod() 来显示一个数字的半值:</p> <p id="demo"></p> <script> Number.prototype.myMethod = function() { return this.valueOf() / 2; }; let n = 55; document.getElementById("demo").innerHTML = n.myMethod(); </script> </body> </html>