fmpq.com
源代码：
点击运行
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Fmpq教程(fmpq.com)</title> </head> <body> <script> var str="Hello world!"; document.write(str.substring(3)+"<br>"); document.write(str.substring(3,7)); </script> </body> </html>
运行结果