源代碼
點擊運行
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>教程</title> </head> <body> <script> var txt="Hello World!"; document.write("<p>" + txt.toUpperCase() + "</p>"); document.write("<p>" + txt.toLowerCase() + "</p>"); document.write("<p>" + txt + "</p>"); </script> <p>該方法返回一個新的字符串,源字符串沒有被改變。</p> </body> </html>
運行結果