Javascript 如何阻止表单提交?
我有以下JavaScript代码Javascript 如何阻止表单提交?,javascript,html,forms,Javascript,Html,Forms,我有以下JavaScript代码 function checkEntries() { if(document.getElementById("username")=="" && document.getElementById("password").value=="") { alert("Please enter username and password"); } if(document.getElementById("user
function checkEntries()
{
if(document.getElementById("username")=="" && document.getElementById("password").value=="")
{
alert("Please enter username and password");
}
if(document.getElementById("username").value=="")
{
alert("Please enter username");
}
if( document.getElementById("password").value=="")
{
alert("Please enter password");
}
}
和HTML代码
<form name="LoginUser" method="post" action="LoginUser" onsubmit="checkEntries()">
<table width="78%" height="90" border="0" cellpadding="0" cellspacing="0">
<tr>
<td width="47%" align="right" class="textstyle">Username:
<label for="username2"></label></td>
<td width="53%" class="textstyle">
<input type="text" name="username" id="username" /><div id="testuser"></div>
</td>
</tr>
<tr>
<td align="right" class="textstyle"> </td>
<td> </td>
</tr>
<tr id="passRow">
<td align="right" class="textstyle">Password:</td>
<td><label for="password"></label>
<input type="password" name="password" id="password"/>
Forgot Password?? Click here...
<div id="testpwd"></div></td>
</tr>
<tr>
<td align="right" class="textstyle"> </td>
<td> </td>
</tr>
<tr>
<td align="right" class="textstyle"> </td>
<td><input type="checkbox" name="rempass" id="rempass" />
<span class="textstyle">Remember my password</span></td>
</tr>
<tr>
<td align="right" class="textstyle"> </td>
<td class="textstyle"> </td>
</tr>
<tr>
<td align="right" class="textstyle"> </td>
<td class="textstyle">
<input type="submit" name="login" id="login" value="Sign in" />
</td>
</tr>
</table>
</form>
JavaScript代码检查用户名和密码是否输入到登录表单中。它工作得很好。但在显示错误后,它会提交表单
如果没有输入用户名和密码,我希望不要提交此表单。它应该只停留在登录页面上。我如何才能做到这一点?试试:
function checkEntries() {
var errFlag = false;
var errMsg = "";
var username = document.getElementById("username");
var password = document.getElementById("password")
if(username == "") {
errMsg += "Please enter username.\n";
errFlag = true;
}
if(password == "") {
errMsg += "Please enter password";
errFlag = true;
}
if(!errFlag) {
return true;
}else {
alert(errMsg);
return false;
}
}
在您的提交上:
<form name="LoginUser" method="post" action="LoginUser" onsubmit="return checkEntries();">
希望有帮助试试:
function checkEntries() {
var errFlag = false;
var errMsg = "";
var username = document.getElementById("username");
var password = document.getElementById("password")
if(username == "") {
errMsg += "Please enter username.\n";
errFlag = true;
}
if(password == "") {
errMsg += "Please enter password";
errFlag = true;
}
if(!errFlag) {
return true;
}else {
alert(errMsg);
return false;
}
}
在您的提交上:
<form name="LoginUser" method="post" action="LoginUser" onsubmit="return checkEntries();">
希望能有所帮助Aahh…谢谢你,伙计。我真傻。我怎么能忘记返回语句D谢谢,伙计,成功了很高兴知道它对你有用。。您可以将答案标记为已接受..:啊…谢谢你,伙计。我真傻。我怎么能忘记返回语句D谢谢,伙计,成功了很高兴知道它对你有用。。您可以将答案标记为已接受..: