jquery内部实现为：
function trim(str){ return str.replace(/^(\s|\u00A0)+/,'').replace(/(\s|\u00A0)+$/,''); }<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=gbk"> <title>JavaScript禁止提交表单</title> <script type="text/javascript"> function getObj(id){ var Obj = document.getElementById(id).value; return Obj; } function check(){ if(getObj("test")==""){ alert("文本框输入为空，不能提交表单！"); document.getElementById("test").focus; return false;//false:阻止提交表单 } } </script> </head> <body> <form action="index.htm" method="post" οnsubmit="return check()"> <input type="text" name="test" id="test"> <input type="submit" value="提交"> </form> </body> </html>
