代码检测textarea内填写的长度，未填写时提示需要重新填写，少于15字符时提示需要长于15字符，成功时显示所填写建议。

<script type="text/javascript">

//jQuery代码

function confirm()

{

if($("#advice").val().length == 0)

{

alert("We can't see your advice. Maybe you should fill the form first.");

$("#advice").focus();

return false;

}

else if($("#advice").val().length <= 15)

{

alert("Your advice should longer than 15 letters.");

$("#advice").focus();

return false;

}

else

{

alert("Thank you for your advice! You will get out reply in 24 hours for advice:n"+$("#advice").val());

return true;

}

}

</script>

<form action="" method="post" onSubmit="return confirm();" >

<textarea id="advice" rows="20" cols="50"placeholder="Give us some advice?"></textarea>

<input type="submit"value="Thank you"/>

</form>

>关键点

1.必须要有onSubmit="return confirm();" return 这个词，不可缺少。

2.自行完整的网页结构。

以上所述就是本文的全部内容了，希望大家能够喜欢。