我是JavaScript的新手，我正在努力绕过这个问题。
我有一个HTML表单，其中包含一些必需的输入字段，这些字段具有onblur验证。我想修复我的代码，以便在没有用户填写这些必填字段的情况下提交表单时，会显示错误消息，而不是当前实际提交的表单。
我意识到有类似的问题，但我无法实施建议的方法，并且已经研究了好几天。我还需要一个纯JavaScript方法，那么如何在单击提交按钮时确保所有空的必填字段都会抛出错误消息？
这是我第一次发帖提问 - 我希望我已经涵盖了所有内容，如果我需要包含其他内容，请告诉我！提前谢谢。
<form id="contact-form" method="POST" action="contact.html" novalidate>
<p>Text</p>
<div class="form-group">
<select name="flights" size="1">
<option value="" disabled selected hidden>Select Flight</option>
<option value="helicopter">Helicopter</option>
<option value="aerobatic">Aerobatic</option>
<option value="tramping">Tramping</option>
<option value="amphibian">Amphibian</option>
<option value="glider">Glider</option>
<option value="private-charter">Private Charter</option>
</select>
</div>
<div class="form-group">
<label>Flight Duration</label>
<br>
<select name="flight-duration" size="1">
<option value="" disabled selected hidden>Select Duration</option>
<option value="helicopter">1 Hour</option>
<option value="tramping">2 Hours</option>
<option value="amphibian">3 Hours</option>
<option value="glider">Custom</option>
</select>
</div>
<div class="form-group">
<label>Booking Date</label>
<br>
<select id="dayDropDown">
</select>
<select id="monthDropDown">
</select>
<select id="yearDropDown">
</select>
</div>
<div class="form-group">
<label for="firstname"></label>
<input id="firstname" type="text" onblur="blur()" name="firstname" placeholder="First Name" required autofocus minlength="2">
<span id="firstname-error"></span>
</div>
<div class="form-group">
<label for="lastname"></label>
<input id="lastname" type="text" name="lastname" placeholder="Last Name" required minlength="2">
<span id="lastname-error"></span>
</div>
<div class="form-group">
<label for="phone"></label>
<input id="phone" type="tel" name="phone" placeholder="Phone Number" required minlength="8">
<span id="phone-error"></span>
</div>
<div class="form-group">
<label for="email"></label>
<input id="email" type="email" name="email" placeholder="Enter valid email address" required>
<span id="email-error"></span>
</div>
<div class="form-group">
<label for="country"></label>
<input id="country" type="text" name="country" placeholder="Country" required minlength="2">
<span id="country-error"></span>
</div>
<div class="form-group">
<textarea placeholder="What can we do for you?"></textarea>
</div>
<div class="form-group">
<button class="submit" type="submit">Submit</button>
</div>
</form>
/****************
*FORM-VALIDATION*
****************/
//convert user input to upper case
function addFormValidation(theForm) {
if (theForm === null || theForm.tagName.toUpperCase() !== 'FORM') {
throw new Error("expected first parameter to addFormValidation to be a FORM.");
}
theForm.noValidate = true;
theForm.addEventListener('submit', function (evt) {
var isError = false;
var elements = this.elements;
for (var i = 0; i < elements.length; i += 1) {
if (!isFieldValid(elements[i])) {
isError = true;
}
}
if (isError) {
evt.preventDefault();
}
});
function isFieldValid(field) {
var errorMessage = "";
function isFieldValid(field) {
if (!needsToBeValidated(field)) {
return true;
}
if (field.id.length === 0 || field.name.length === 0) {
console.error("error: ", field);
throw new Error("found a field that is missing an id and/or name attribute." +
" name should be there. id is required for determining the field's error message element.");
}
field.classList.remove('invalid');
var errorSpan = document.querySelector('#' + field.id + '-error');
if (errorSpan === null) {
console.error("error: ", field);
throw new Error("could not find the '#" + field.id + "-error' element. It's needed for error messages if #" + field.id + " is ever invalid.");
}
errorSpan.classList.remove('danger');
errorSpan.innerHTML = "";
if (field.minLength > 0 && field.value.length < field.minLength) {
errorMessage = "Must be " + field.minLength + " or more characters long.";
}
if (field.maxLength > -1 && field.value.length > field.maxLength) {
errorMessage = "Must be " + field.maxLength + " characters or less.";
}
if (field.type === "email" && !isEmail(field.value)) {
errorMessage = "This should be a valid email address.";
}
if (field.required && field.value.trim() === "") {
errorMessage = "This field is required.";
}
if (errorMessage !== "") {
field.classList.add('invalid');
errorSpan.classList.add('danger');
errorSpan.innerHTML = errorMessage;
return false;
}
return true;
}
//fields that do not require validation
// function needsToBeValidated(field) {
// return ['submit', 'reset', 'button', 'hidden', 'radio', 'fieldset', 'select'].indexOf(field.type) === -1;
// }
function needsToBeValidated(field) {
return ['submit', 'reset', 'button', 'hidden', 'fieldset'].indexOf(field.type) === -1;
}
//email regx pattern to ensure email input is a valid email
function isEmail(input) {
return input.match(/^([a-z0-9_.\-+]+)@([\da-z.\-]+)\.([a-z\.]{2,})$/);
}
//add onblur validation to provide error/success info for user
var elements = theForm.elements;
for (var j = 0; j < elements.length; j++) {
elements[j].addEventListener('blur', function () {
isFieldValid(event.target);
})
};
}
//wait for content to load before loading form
document.addEventListener('DOMContentLoaded', function () {
addFormValidation(document.querySelector('#contact-form'))
});
/***********************************************
* Implemented this date selector script for use on contact form:
* Drop Down Date select script- by JavaScriptKit.com
* This notice MUST stay intact for use
* Visit JavaScript Kit at http://www.javascriptkit.com/ for this script and more
***********************************************/
var monthtext = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sept', 'Oct', 'Nov', 'Dec'];
function populatedropdown(dayfield, monthfield, yearfield) {
var today = new Date()
var dayfield = document.getElementById(dayfield)
var monthfield = document.getElementById(monthfield)
var yearfield = document.getElementById(yearfield)
for (var i = 0; i < 31; i++)
dayfield.options[i] = new Option(i, i + 1)
dayfield.options[today.getDate()] = new Option(today.getDate(), today.getDate(), true, true) //select today's day
for (var m = 0; m < 12; m++)
monthfield.options[m] = new Option(monthtext[m], monthtext[m])
monthfield.options[today.getMonth()] = new Option(monthtext[today.getMonth()], monthtext[today.getMonth()], true, true) //select today's month
var thisyear = today.getFullYear()
for (var y = 0; y < 20; y++) {
yearfield.options[y] = new Option(thisyear, thisyear)
thisyear += 1
}
yearfield.options[0] = new Option(today.getFullYear(), today.getFullYear(), true, true) //select today's year
}
//populatedropdown(id_of_day_select, id_of_month_select, id_of_year_select)
window.onload = function () {
populatedropdown("dayDropDown", "monthDropDown", "yearDropDown")
}
答案 0 :(得分：0)
您必须在代码中调用javascript验证函数。
<form name="" method="" onsumbmit="return myfunction()">
<!-- Your code -->
</form>
在你的javascript代码中，如果一切正常，则返回true，否则返回false并显示相应的消息。
function myfunction(){
<!-- here your validation conditions -->>
if(everything==ok)
return true;
else
return false;
}
答案 1 :(得分：0)
删除表单上的novalidate属性。