此方法检查字符串是否以子字符串开头。
string.startsWith(substring);
返回布尔值。
<html> <head> <title>Prototype examples</title> <script type = "text/javascript" src = "/javascript/prototype.js"></script> <script> function showResult() { var str = "Prototype JavaScript"; alert ("First Check : " + str.startsWith("JavaScript") ); alert ("Second Check : " + str.startsWith("Prototype") ); } </script> </head> <body> <p>Click the button to see the result.</p> <br /> <br /> <input type = "button" value = "Result" onclick = "showResult();"/> </body> </html>