JQuery阻止表单提交的方法总结 - 使用onsubmit()验证表单并阻止非法提交

方法1：<form onsubmit="javascript:confirm()"> 方法内返回false阻止表单提交

示例：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。

 1 <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>
28　　 <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。

---

方法二：<form onsubmit="javascript:checkContent(this, event)"> 方法内返回false阻止表单提交

evt.preventDefault(); 使用JQuery event对象的方法preventDefault()阻止默认行为

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gAG7bZMFS8q+Vb/vzzz8Pdbv/cPe+qNcPQVJEWm73MIxQAW7LNMFS74RXvZ1aGtuTClaFgLwC2apth6CC41eUh6bAyVItNrF9xSJxxWTuTNAAbsMEwFC8LzW5p6Zb8CVcnXhnK824+AKbTpSCDAWDzNhiG9tJ72FT5PtDs7hiU5Fp0hqF/6tl3yj42NR4Atm2bYSj/XX+2fVZmf49MH938rlQzH/eHoen0+/WGBMBWbTAM5es9/4R3vtlLYeiqxZ+cxh+THQqn6Wfy12QAW7fBMDRT+5ijeDsUhq7d235Mlr8EYHu2GYaCX/qLL4trSFwjYQiApbYZhmaKwWj21uGllaGrdslfk/1jAAAMaZthqHarK5b5p3QLdDu8UvGQqP1RYW2BsGcgAXDtthmGGJYhAcBSwhCbYkgAsJQwxKYYEgAsJQyxKYYEAEsJQ2yKIQHAUsIQm2JIALDU1YchAIALXXcYuvyIbIkhAcBSwhCbYkgAsJQwxKYYEgAsJQyxKYYEAEsJQ2yKIQHAUsIQm2JIALCUMMSmGBIALCUMsSmGBABLCUNsiiEBwFLCEJvSHBLTVB2lU93SZvTvckblv7u2nkribmyWjMvU+r9Z8yUt32+/pAN7TnxRgQ+0tCfj8heOqJ4yi8bGJZemf4pYdEQ+nDC0yF9/fPr0x1/ve0yW6BkStZtrscx50kM0Q1VtJk336gxnnZN4+vKM9sQ3g+k0VcS3peKW2b6zzuzZMW92fHb5sc7TbE//u79ZNJV1XqD8saZ5psFF+R2jbjai+n8KOhu/tH9YA2FokR+7aWcxas3iIRHMmP3Tbo/aIfqPNauhWE9w3Py8nvrm6Hjuzs9rVrKnQN6r+bmnT4KuaJ5+Z5ng0jQrLNbWrKd5Lr9ZdSqLh+WsZPF5fz2dx5reYtTlB306vQpBY2blOzsh7h/WZrNh6K8/Pr2O4f3P/OlvQn/98Wl6eZmV3Jfd7Q6bXwr+2CU/GBaI1qknDOXPn04nxNrLTrXZszZTFxs5K3z2nFuc9IvVNqtKT212kyieY/N20txSfBnoKVBsedAnl6tdlNq7Mx81ldUaVrusxfHQrKpn+1uNunwg9V/3RfUs7R/WYJthKJkfjjNH+qvQj93L+8WSTz92yRTx1x+fipMQa1QbEvl81zP3ne2M2bZYQ22WrzU1L1OcoA9bgjbHDS6+Nbv3FEvmrS2edfN20uyK4lnXTrN/YNTUjlJsVe1J7p2nsrzni334dNpptRPpL5A3o39756grvpsPodjsRGbHXdo/rMoWw9DxR35/ii8zx/Hn//CsUvJ0BflYyIdk69cZhoL5azbNFafL5hzanDSbt5x4ni0eK3+r2ID01IqnE8zpQYPjBsStrd0t4pc9BYIyxX6enWZeVed1D2quFS7U/EFTWXwWT5UhlBd7qndyetbNEXX5qHs6ve6H3WenEKv1Q/EQ/f1TuO58hA2GoWSt+MXxl6Tdj9mvR6WSs9+aDvOGhaErsDQMPZVmqFixkvTd2hxaO1CtnmLL8/I9d4X4sac9QZlFt6W8c4rtLBaLK++5XT1VLl/PeIive/GtuCeb/fwhU1l6msVuKY7M/OcrFvdAz/alo652jrXDxRtrZx2XiZvBx9poGCr+1rOfAZLfiSols9+mDr97yUKrVxwS8dxXuwEXp++8tqJ40uypJ6+h2JjZ7rW7Qr77GbeBnv6JOzNobdxF8dk1a2hevrgPgx2XtqdWuOj9p7L08uXtDHopHk75oC1WUjziW426vHyx2fFVnpXvqSfon54RxbvZYBh6+rGbkingxy75eP3Tp0/p9wWLJSsTiDB0FZpfoO6cd+JizXp6boq1GT9/t1hhcKy8qWkl+WPQ+P4TDBqwqLU9jZ+VrxWIb3JByfxypG891TUrD0624KOnsuL5BsO1dkGDd2tq7Wk+r23JD1psWHpGtdOsHeVQ26L+aQ8D3sUWw9DponH57y7qJWsry0lZmWi9+v+arPhy0dQcH6U4D9am3WIltVk4OIvaXaH42HPLKTYp6J9aA5a2Nm9e8XZyKFbr2Fkja0ePW9Wv2MhanT0Hev+prDbsm0M3OOvaUO8ZgW8y6oL21JrUvGQ9+77VuOIdbDMMMaxgSMTz+1M2hcXTYiDdPa6zdu8M2rborWKx4KDNSpplmrel2v0saGTQV0vvOrVib3LTanZs0JjVCq5U3mm1kFHLEP2jaOn24qgrNibfq/+nMng37h9WSBhiU+IvUD+FN+PanXjRFBZPtfmcOJX0l4nVTj9vW+0UagUuuS3Vntf6P9irf8tTqROarerXc716GvnheppdvFLplnyXnmP1H7dZf2fJeDTmTQoaPCuT1tnsH9ZAGGJTDAkAlhKG2BRDAoClhCE2xZAAYClhiE0xJABYShhiUwwJAJYShtgUQwKApYQhNsWQAGCpqw9DAAAXuuIwBADwzoQhAGBowhAAMDRhCAAYmjAEAAxNGAIAhiYMAQBDE4YAgKEJQwDA0IQhAGBowhAAMDRhCAAYmjAEAAxNGAIAhiYMAQBDE4YAgKEJQwDA0IQhAGBowhAAMDRhCAAY2rrC0A8AgIsJQwDA0K44DAEAvDNhCAAYmjAEAAxNGAIAhiYMAQBDE4YAgKEJQwDA0IQhAGBowhAAMDRhCAAYmjAEAAxNGAIAhiYMAQBDi5PM/wOqqPhpmNKfkwAAAABJRU5ErkJggg==" alt="" />

参考W3School教程

示例：

<script type="text/javascript">
//jQuery代码
function checkContent(form, evt)
{
　　if($("#advice").val().length == 0)
　　{
　　　　alert("We can't see your advice. Maybe you should fill the form first.");
　　　　$("#advice").focus();
　　　　evt.preventDefault();
　　}else if($("#advice").val().length <= 15)
　　{
　　　　alert("Your advice should longer than 15 letters.");
　　　　$("#advice").focus();
　　　　evt.preventDefault();

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

</script> 

<form action="" method="post" onSubmit="javascript:checkContent(this, event)" > 　　
　　<textarea id="advice" rows="20" cols="50" placeholder="Give us some advice?"></textarea> 　
　　　　<input type="submit" value="Thank you"/> 
</form>