问题
Hi there I am really stuck on this and since I am a javscript beginner this boggles my mind.
Is there someone who knows how to write the following javascript form validation? I am sure that it is very simple, but I can not figure this one out to save my life.
Thank you for you sharing your knowledge.
I need to write WITHOUT jquery the following form validation. Whenever an error is encountered, prevent the form from being submitted. I need to use the window.onload function to assign a validation callback function. There are 4 inputs which get validated by the javascript code. Also the javascript needs to be in its own file.
Validation Rules are as follow:
INPUT: Username; Required (yes); Validation (Must be 5-10 characters long). INPUT: Email; Required (yes); Validation (Must have an @ sign, must have a period). INPUT: Street name; Required (no); Validation (Must start with a number). INPUT: Year of birth; Required (yes); Validation (must be numeric).
My code looks as follow:
HTML:
<!DOCTYPE html>
<html>
<head>
<script defer="defer" type="text/javascript" src="form.js"></script>
</head>
<body>
<form action="fake.php">
Username*: <input type="text" class="required" name="u"/><br/>
Email*: <input type="text" class="required" name="p"/><br/>
Street address: <input type="text" class="numeric" name="s"/><br/>
Year of birth*: <input type="text" class="required numeric" name="b"/><br/>
<input type="submit"/><br/>
</form>
</body>
</html>
JS
document.forms[0].elements[0].focus();
document.forms[0].onsubmit=function(){
for(var i = 0; i < document.forms[0].elements.length; i++){
var el = document.forms[0].elements[i];
if((el.className.indexOf("required") != -1) &&
(el.value == "")){
alert("missing required field");
el.focus();
el.style.backgroundColor="yellow";
return false;
}
if((el.className.indexOf("numeric") != -1) &&
(isNaN(el.value))){
alert(el.value + " is not a number");
el.focus();
el.style.backgroundColor="pink";
return false;
}
}
}
回答1:
without changing much of your code ... updated your code for other validation like length (needs a class verifylength to validate length) and so on....
try this
HTML
<form action="fake.php">Username*:
<input type="text" class="required verifylength" name="u" />
<br/>Email*:
<input type="text" class="required email" name="p" />
<br/>Street address:
<input type="text" class="numeric" name="s" />
<br/>Year of birth*:
<input type="text" class="required numeric" name="b" />
<br/>
<input type="submit" />
<br/>
</form>
JAVASCRIPT
document.forms[0].elements[0].focus();
document.forms[0].onsubmit = function () {
for (var i = 0; i < document.forms[0].elements.length; i++) {
var el = document.forms[0].elements[i];
if ((el.className.indexOf("required") != -1) && (el.value == "")) {
alert("missing required field");
el.focus();
el.style.backgroundColor = "yellow";
return false;
} else {
if (el.className.indexOf("verifylength") != -1) {
if (el.value.length < 5 || el.value.length > 10) {
alert("'" + el.value + "' must be 5-10 charater long");
el.focus();
el.style.backgroundColor = "pink";
return false;
}
}
}
if (el.className.indexOf("email") != -1) {
var regEx = /^([0-9a-zA-Z]([-.\w]*[0-9a-zA-Z])*@([0-9a-zA-Z][-\w]*[0-9a-zA-Z]\.)+[a-zA-Z]{2,9})$/;
var emailTest = regEx.test(el.value);
if (!emailTest) {
alert("email not valid");
el.focus();
el.style.backgroundColor = "yellow";
return false;
}
};
if ((el.className.indexOf("numeric") != -1) && (isNaN(el.value))) {
alert(el.value + " is not a number");
el.focus();
el.style.backgroundColor = "pink";
return false;
}
}
}
working fiddle
回答2:
something alongs the lines of...
//username 5-10 chars
var uVal = document.getElementsByTagName("u").value;
if (uVal.length < 5 || uVal.length > 10) return false;
//email needs @ and .
var eVal = document.getElementsByTagName("p").value;
if !(eVal.match('/.*@.*\./g')) return false;
//street starts w/ num
var sVal = document.getElementsByTagName("s").value;
if !(sVal.match('/^[0-9]/g')) return false;
i think the regex is off + untested :)
回答3:
Here is your javascript validation object in work. Hope you can make some modification according to your need.
Style
<style>
.valid {border: #0C0 solid 1px;}
.invalid {border: #F00 solid 1px;}
</style>
HTML Form
<div>
<form id="ourForm">
<label>First Name</label><input type="text" name="firstname" id="firstname" class="" /><br />
<label>Last Name</label><input type="text" name="lastname" id="lastname" class="" /><br />
<label>Username</label><input type="text" name="username" id="username" class="" /><br />
<label>Email</label><input type="text" name="email" id="email" class="" /><br />
<input type="submit" value="submit" class="" />
</form>
</div>
Call script before closing tag
<script src="form_validation_object.js"></script>
form_validation_object.js
/*
to: dom object
type: type of event
fn: function to run when the event is called
*/
function addEvent(to, type, fn) {
if (document.addEventListener) { // FF/Chrome etc and Latest version of IE9+
to.addEventListener(type, fn, false);
} else if (document.attachEvent) { //Old versions of IE. The attachEvent method has been deprecated and samples have been removed.
to.attachEvent('on' + type, fn);
} else { // IE5
to['on' + type] = fn;
}
}
// Your window load event call
addEvent(window, 'load', function() {
/* form validation object */
var Form = {
validClass: 'valid',
inValidClass: 'invalid',
fname: {
minLength: 1,
maxLength: 8,
fieldName: 'First Name'
},
lname: {
minLength: 1,
maxLength: 12,
fieldName: 'Last Name'
},
username: {
minLength: 5,
maxLength: 10,
fieldName: 'Username'
},
validateLength: function(formElm, type) {
//console.log('string = ' + formElm.value);
//console.log('string length = ' + formElm.value.length);
//console.log('max length=' + type.maxLength);
//console.log(Form.validClass);
if (formElm.value.length > type.maxLength || formElm.value.length < type.minLength) {
//console.log('invalid');
//alert(formElm.className);
if (formElm.className.indexOf(Form.inValidClass) == -1) {
if (formElm.className.indexOf(Form.validClass) != -1) {
formElm.className = formElm.className.replace(Form.validClass, Form.inValidClass);
} else {
formElm.className = Form.inValidClass;
}
}
//alert(formElm.className);
return false;
} else {
//console.log('valid');
//alert(formElm.className.indexOf(Form.validClass));
if (formElm.className.indexOf("\\b" + Form.validClass + "\\b") == -1) { // regex boundary to match whole word only http://www.regular-expressions.info/wordboundaries.html
//formElm.className += ' ' + Form.validClass;
//alert(formElm.className);
if (formElm.className.indexOf(Form.inValidClass) != -1)
formElm.className = formElm.className.replace(Form.inValidClass, Form.validClass);
else
formElm.className = Form.validClass;
}
return true;
}
},
validateEmail: function(formElm) {
var regEx = /^([0-9a-zA-Z]([-.\w]*[0-9a-zA-Z])*@([0-9a-zA-Z][-\w]*[0-9a-zA-Z]\.)+[a-zA-Z]{2,9})$/;
var emailTest = regEx.test(formElm.value);
if (emailTest) {
if (formElm.className.indexOf(Form.validClass) == -1) {
formElm.className = Form.validClass;
}
return true;
} else {
formElm.className = Form.inValidClass;
return false;
}
},
getSubmit: function(formID) {
var inputs = document.getElementById(formID).getElementsByTagName('input');
for (var i = 0; i < inputs.length; i++) {
if (inputs[i].type == 'submit') {
return inputs[i];
}
}
return false;
}
}
/* call validation object */
var ourForm = document.getElementById('ourForm');
var submit_button = Form.getSubmit('ourForm');
submit_button.disabled = 'disabled';
function checkForm() {
var inputs = ourForm.getElementsByTagName('input');
if (Form.validateLength(inputs[0], Form.fname)) {
if (Form.validateLength(inputs[1], Form.lname)) {
if (Form.validateLength(inputs[2], Form.username)) {
if (Form.validateEmail(inputs[3])) {
submit_button.disabled = false;
return true;
}
}
}
}
submit_button.disabled = 'disabled';
return false;
}
checkForm();
addEvent(ourForm, 'keyup', checkForm);
addEvent(ourForm, 'submit', checkForm);
});
Working example at JSBin
http://jsbin.com/ezujog/1
来源：https://stackoverflow.com/questions/15696938/form-validation-with-javascript-using-window-onload