题目：将：“America”、“Greece”、“Britain”、“Canada”、“China”、“Egypt”各个字符串 统一改为大写
toUpperCase() 方法用于把字符串转换为大写。
1<!DOCTYPE html> 2<html lang="en"> 3 4<head> 5 <meta charset="UTF-8"> 6 <meta http-equiv="X-UA-Compatible" content="IE=edge"> 7 <meta name="viewport" content="width=device-width, initial-scale=1.0"> 8 <title>Document</title> 9</head> 10<body> 11 <script type="text/javascript"> 12 var str="America, Greece, Britain,Canada,China,Egypt"; 13 document.write(str+"<br/>"); 14 document.write(str.toUpperCase()); 15 16 </script> 17</body> 18</html>
结果：