我尝试使用JavaScript进行表单验证，但是我似乎没有得到任何回复，即使是在那里也没有提醒。
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Example Form</title>
<script type="text/javascript">
function CheckForBlank() {
if(document.getElementById('name').value="") {
alert("enter something valid");
return false;
}
}
</script>
</head>
<body>
<form method="post" action="2013.php" onsubmit="return CheckForBlank();">
Name: <input type="text" name="name" id="name"/>
Age: <input type="text" name="age" id="age"/>
Email: <input type="text" name="email" id="email"/>
<p><input type="submit" value="Submit" /></p>
</form>
</body>
</html>
答案 0 :(得分：4)
在javascript中使用===或==进行条件检查。
if(document.getElementById('name').value === ""){
alert("enter something valid");
return false;
}
答案 1 :(得分：2)
你必须使用==进行比较。=用于分配
if(document.getElementById('name').value == ""){
alert("enter something valid");
return false;
}
答案 2 :(得分：1)
此处您的问题仅针对if条件！您必须在JavaScript中使用==或===进行比较。
以下是更正的脚本！
function CheckForBlank() {
if(document.getElementById('name').value=="") {
alert("enter something valid");
return false;
}
}
如果您删除或避免return false，表单将回发即使验证失败！所以，return false意味着，在if之后退出函数是必须的，并且在另一个答案中错过了!!
答案 3 :(得分：1)
您正在使用=作为赋值运算符，使用==比较运算符可以正常工作
<head>
<title>Example Form</title>
<script type="text/javascript">
function CheckForBlank() {
if(document.getElementById('name').value=="") {
alert("enter something valid");
return false;
}
}
</script>
</head>
<body>
<form method="post" onsubmit="return CheckForBlank();">
Name: <input type="text" name="name" id="name"/>
Age: <input type="text" name="age" id="age"/>
Email: <input type="text" name="email" id="email"/>
<p><input type="submit" value="Submit" /></p>
</form>
</body>
答案 4 :(得分：0)
尽管您将Javascript附加到表单提交事件，而不是按钮提交事件，但我不敢相信直到现在还没有意识到这一点。正常的浏览器验证有效（即输入[type =“ email]，required =” required“等）。
在Firefox和Chrome中工作。
// jQuery example attaching to a form with the ID form
$(document).on("submit", "#form", function(e) {
e.preventDefault();
console.log ("Submitted! Now serialise your form and AJAX submit here...");
})
答案 5 :(得分：-1)
我已经使用bootstrap做了更好的表单验证方法。您可以查看我的代码集http://codepen.io/abhilashn/pen/bgpGRw
var g_UnFocusElementStyle = "";
var g_FocusBackColor = "#FFC";
var g_reEmail = /^[\w\.=-]+\@[\w\.-]+.[a-z]{2,4}$/;
var g_reCell = /^\d{10}$/;
var g_invalidFields = 0;
function initFormElements(sValidElems) {
var inputElems = document.getElementsByTagName('textarea');
for(var i = 0; i < inputElems.length; i++) {
com_abhi.EVENTS.addEventHandler(inputElems[i], 'focus', highlightFormElement, false);
com_abhi.EVENTS.addEventHandler(inputElems[i], 'blur', unHightlightFormElement, false);
}
/* Add the code for the input elements */
inputElems = document.getElementsByTagName('input');
for(var i = 0; i < inputElems.length; i++) {
if(sValidElems.indexOf(inputElems[i].getAttribute('type') != -1)) {
com_abhi.EVENTS.addEventHandler(inputElems[i], 'focus', highlightFormElement, false);
com_abhi.EVENTS.addEventHandler(inputElems[i], 'blur', unHightlightFormElement, false);
}
}
/* submit handler */
com_abhi.EVENTS.addEventHandler(document.getElementById('form1'), 'submit' , validateAllfields, false);
/* Add the default focus handler */
document.getElementsByTagName('input')[0].focus();
/* Add the event handlers for validation */
com_abhi.EVENTS.addEventHandler(document.forms[0].firstName, 'blur', validateFirstName, false);
com_abhi.EVENTS.addEventHandler(document.forms[0].email, 'blur', validateEmailAddress, false);
com_abhi.EVENTS.addEventHandler(document.forms[0].address, 'blur', validateAddress, false);
com_abhi.EVENTS.addEventHandler(document.forms[0].cellPhone, 'blur', validateCellPhone, false);
}
function highlightFormElement(evt) {
var elem = com_abhi.EVENTS.getEventTarget(evt);
if(elem != null) {
elem.style.backgroundColor = g_FocusBackColor;
}
}
function unHightlightFormElement(evt) {
var elem = com_abhi.EVENTS.getEventTarget(evt);
if(elem != null) {
elem.style.backgroundColor = "";
}
}
function validateAddress() {
var formField = document.getElementById('address');
var ok = (formField.value != null && formField.value.length != 0);
var grpEle = document.getElementById('grpAddress');
if(grpEle != null) {
if(ok) {
grpEle.className = "form-group has-success has-feedback";
document.getElementById('addressIcon').className = "glyphicon glyphicon-ok form-control-feedback";
document.getElementById('addressErrorMsg').innerHTML = "";
}
else {
grpEle.className = "form-group has-error has-feedback";
document.getElementById('addressIcon').className = "glyphicon glyphicon-remove form-control-feedback";
document.getElementById('addressErrorMsg').innerHTML = "Please enter your address";
}
return ok;
}
}
function validateFirstName() {
var formField = document.getElementById('firstName');
var ok = (formField.value != null && formField.value.length != 0);
var grpEle = document.getElementById('grpfirstName');
if(grpEle != null) {
if(ok) {
grpEle.className = "form-group has-success has-feedback";
document.getElementById('firstNameIcon').className = "glyphicon glyphicon-ok form-control-feedback";
document.getElementById('firstNameErrorMsg').innerHTML = "";
}
else {
grpEle.className = "form-group has-error has-feedback";
document.getElementById('firstNameIcon').className = "glyphicon glyphicon-remove form-control-feedback";
document.getElementById('firstNameErrorMsg').innerHTML = "Please enter your first name";
}
return ok;
}
}
function validateEmailAddress() {
var formField = document.getElementById('email');
var ok = (formField.value.length != 0 && g_reEmail.test(formField.value));
var grpEle = document.getElementById('grpEmail');
if(grpEle != null) {
if(ok) {
grpEle.className = "form-group has-success has-feedback";
document.getElementById('EmailIcon').className = "glyphicon glyphicon-ok form-control-feedback";
document.getElementById('emailErrorMsg').innerHTML = "";
}
else {
grpEle.className = "form-group has-error has-feedback";
document.getElementById('EmailIcon').className = "glyphicon glyphicon-remove form-control-feedback";
document.getElementById('emailErrorMsg').innerHTML = "Please enter your valid email id";
}
}
return ok;
}
function validateCellPhone() {
var formField = document.getElementById('cellPhone');
var ok = (formField.value.length != 0 && g_reCell.test(formField.value));
var grpEle = document.getElementById('grpCellPhone');
if(grpEle != null) {
if(ok) {
grpEle.className = "form-group has-success has-feedback";
document.getElementById('cellPhoneIcon').className = "glyphicon glyphicon-ok form-control-feedback";
document.getElementById('cellPhoneErrorMsg').innerHTML = "";
}
else {
grpEle.className = "form-group has-error has-feedback";
document.getElementById('cellPhoneIcon').className = "glyphicon glyphicon-remove form-control-feedback";
document.getElementById('cellPhoneErrorMsg').innerHTML = "Please enter your valid mobile number";
}
}
return ok;
}
function validateAllfields(e) {
/* Need to do it this way to make sure all the functions execute */
var bOK = validateFirstName();
bOK &= validateEmailAddress();
bOK &= validateCellPhone();
bOK &= validateAddress();
if(!bOK) {
alert("The fields that are marked bold and red are required. Please supply valid\n values for these fields before sending.");
com_abhi.EVENTS.preventDefault(e);
}
}
com_abhi.EVENTS.addEventHandler(window, "load", function() { initFormElements("text"); }, false);<link href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" rel="stylesheet"/>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="container">
<div class="row">
<h1 class="text-center">Interactive form validation using bootstrap</h1>
<form id="form1" action="" method="post" name="form1" class="form-horizontal" role="form" style="margin:10px 0 10px 0">
<div id="grpfirstName" class="form-group">
<label for="firstName" class="col-sm-2 control-label"><span class="text-danger">* </span>First Name</label>
<div class="col-sm-10">
<input type="text" class="form-control" id="firstName" placeholder="Enter first name">
<span id="firstNameIcon" class=""></span>
<div id="firstNameErrorMsg" class="text-danger"></div>
</div>
</div>
<div class="form-group">
<label for="lastName" class="col-sm-2 control-label">Last Name</label>
<div class="col-sm-10">
<input type="text" class="form-control" id="lastName" placeholder="Enter last name">
</div>
</div>
<div id="grpEmail" class="form-group">
<label for="lastName" class="col-sm-2 control-label"><span class="text-danger">* </span>Email </label>
<div class="col-sm-10">
<input type="email" class="form-control" id="email" placeholder="Enter email">
<span id="EmailIcon" class=""></span>
<div id="emailErrorMsg" class="text-danger"></div>
</div>
</div>
<div id="grpCellPhone" class="form-group">
<label for="lastName" class="col-sm-2 control-label"><span class="text-danger">* </span>Cell Phone </label>
<div class="col-sm-10">
<input type="text" class="form-control" id="cellPhone" placeholder="Enter Mobile number">
<span id="cellPhoneIcon" class=""></span>
<div id="cellPhoneErrorMsg" class="text-danger"></div>
</div>
</div>
<div class="form-group" id="grpAddress">
<label for="address" class="col-sm-2 control-label"><span class="text-danger">* </span>Address </label>
<div class="col-sm-10">
<textarea id="address" class="form-control"></textarea>
<span id="addressIcon" class=""></span>
<div id="addressErrorMsg" class="text-danger"></div>
</div>
</div>
<div class="form-group">
<div class="col-sm-offset-2 col-sm-10">
<button type="submit" class="btn btn-success">Save</button>
</div>
</div>
</form>
</div> <!-- End of row -->
</div> <!-- End of container -->
请检查我的codepen以更好地理解代码。