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prevent form from POSTing until javascript code is satisfied
(4 answers)
Closed 9 years ago.
Is there a way that I can use javascript to prevent a form from runing a php script. For example something like this:
<form action="somePage.php" method="POST>
<input type= "text" class= "field" name = "blah">
<input type="submit" value="Send" >
</form>
I know how to validate what's in that text box using javascript, but I want to prevent the somePage.php to run if the text box is empty. I haven't really tried anything cause I just don't know how to do it.
Hope you guys understand my problem.
Thanks
You can attach function to submit event of the form:
document.getElementById('form-id').addEventListener("submit", function(e){
var field1 = getElementById('field1').value;
if(field1=='' || field1 == null){
e.preventDefault();
alert('Pls fill the required fields.');
return;
}
return true;
});
OR
Below solution uses inline js:
If you want to run your js function before submitting the form to php script, you can use onsubmit attribute of the form,
<form id="form-id" action="somePage.php" method="POST" onsubmit="return formSubmit();">
<input type= "text" class= "field" id="field1" name = "blah">
<input type="submit" value="Send" >
</form>
In formSubmit function you can check the value of the input, if its empty or not, and if empty, then you can just return false;
var formSubmit = function(){
var field1 = getElementById('field1').value;
if(field1=='' || field1 == null)
return false;
else
return true;
}
You simply need to return false for your submit event by grabbing the form (I used querySelector because you have no IDs or classes), and adding a submit listening event to return false.
var x = document.querySelector("[method='POST']");
x.addEventListener("submit",function() {
return false;
});
Use this code to prevent form from submitting:
var first_form = document.getElementsByTagName('form')[0];
first_form.addEventListener('submit', function (e) {
e.preventDefault(); //This actually prevent browser default behaviour
alert('Don\'t submit');
//Do your stuff here
}, false);
Better read docs
you could in your somePage.php have this be a clause somewhere new the beggin:
if(empty($_POST['blah'])){
die();
}
or the inverse of
if(!empty($_POST['blah'])){
//do what this php is supposed to
}
else{
//display error
}
this will prevent your php from running if that field is not filled out.
Personally I return them to the same page setting some error on the page.
Related
I am trying to check if all form fields are filled on click a button & if valid then i am trying to add a check an alert using jquery.
jQuery("button#btn_place_order").click(function(event){
jQuery("form").validate({
submitHandler: function(form) {
alert('ok');
}
});
});
This is what i have tried but its not working, i just want to check if all fields are ok valid & filled & there is no form related error then just console or alert to check. Webpage has two or more html forms. Is their any way we can check using jquery ?
Thanks
First of you will have to prevent the default behavior of a form submit. Afterwards add a event listener to your button and check for validation of each input. (whatever that means for you). Is this what you wanted?
var el = document.getElementById("form");
el.addEventListener("submit", function(event) {
event.preventDefault();
}, true);
document.getElementById("btn").addEventListener("click", validate);
function validate(){
let valid = true;
[...document.getElementById("form").elements].forEach((input) => {
if(input.value.length == 0){
valid = false;
}
});
if(valid) alert("valid");
}
<form id="form">
<input type="text" name="TEST" id="test">
</form>
<button class="button" name="Send" value="Send" id="btn">Check</button>
I have this email form, with "Sender, "Subject" and "Message".
But i haven't linked it to make sure they have written something, so if someone press the "Send" button without typing anyting, i get a blank email. So i want it to abort the email sending if the textbox is empty, and send it if it contains any text.
code for the send button:
<input type="submit" name="submit" value="Submit" class="submit-button" />
ID for the textbox is: textbox_text
You can use jquery to validate the form like this-
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<form action="" method="post">
Sender
<input type="text">
<br/>Subject
<input type="text">
<br/>Message
<input type="text" id="txtMessage">
<br/>
<input type="submit" value="Send" name="btnSend">
</form>
<script type="text/javascript">
$(document).ready(function() {
$("input[name=btnSend]").click(function() {
var msg = $("#txtMessage").val();
if (msg == "") {
alert("Please enter the message");
return false;
}
});
});
</script>
Java Script function
<script type="text/javascript">
function IsEmpty()
{
if(document.forms['frm'].textbox_text.value == "")
{
alert('Message body is empty');
return false;
}
return true;
}
</script>
HTML
<form name="frm">
<input type="submit" name="submit" onclick="return IsEmpty();" value="Submit" class="submit-button" />
</form>
EDIT Check textbox2 in if condition
if(document.forms['frm'].textbox1.value == "" && document.forms['frm'].textbox2.value == "")
I dont know this is your exact answer but it will helps you to validate:
$('#checkSubmit').click(function(){
var chec=$("#textContent").val();
if(chec=="")
alert("Please add your content");
else
alert("successfully submitted");
});
check out this fiddle:
http://jsfiddle.net/0t3oovoa/
You need to check that on server side (with php) and you can also check it on client side(Javascript).
Client side test is good if you want the user to get fast response, but you still need to check it on server side because javascript on your website can ALWAYS be changed by user.
You could also just add "required" on your input elements.
for server side check with php:
<?php
//Check if variables exist
if(isset($_POST['sender']) && isset($_POST['subject']) && isset($_POST['message'])){
//Check if sender value is empty
if(empty($_POST['sender'])){
//If empty, go back to form.Display error with $_GET['error'] in your form page
header('location: backToFormPage.php?error=send');
}
//...
}
//Variables doesn't exist
else{
//Redirect to page or other action
}
?>
You can achieve it two ways:
1. Client Side( Which i recommend) use the form validation to validate the form data if it is empty tell them to fill it. You chose the submit button to trigger validation that is not recommended instead validation is triggered on form submission or on change of input elements(for real-time validation). Anyways below is an example for validation using the click event on submit button.
var validateTextBox = function(textBox) {
var val = textBox.value;
if(val=="") { // Check for empty textbox
return false;
}
return true;
}
documnet.querySelector('#SubmitButton').onclick(function () {
var textbox = document.querySelector("#SubjectORMessage").value;
if(validateTextBox(textbox)){
// Do something to let page know that form is valid
} else {
// Let the user know that he has done something wrong
alert("Please fill the content");
}
})
2. Server Side if unfortunately empty data is send to the server, then use server side validation (Server side validation requires a little more thing to do at more than one place, i.e., html, php/python/perl)
I am checking the textbox value in javascript. and saving to database. where as my save is of submit type. I want if textbox value is greater than 100 then it should alert. and after alert , page should not submit.
Firstly, bind the click event of that button to a function. Secondly, use event.prevent default to stop that button from submitting the form. Thirdly, validate the value you want. If validated, use form id to submit the form. Something like this:
$("#ButtonId").on("click", function(event) {
event.preventDefault ? event.preventDefault() : event.returnValue = false;
if ($("#InputBoxID").val() < 100) {
$("#FormId").submit();
}
else {
alert("your message");
}
});
Above code is in jQuery, so do not forget to add the reference to jQuery.
I think you're looking for something like:
<form id="myForm" onsubmit="return validateForm();">
<input type="text" id="textfield"/>
<button type="submit">submit</button>
</form>
<script>
function validateForm(){
var value=parseInt(document.getElementById('textfield').value);
if(value>100){
alert('value is no good. larger then 100');
return false;
}
}
</script>
If you can show me your code I'd be happy to help you implementing such a feature.
Here you have an example of how to do it. I used a limit of 10 characters to make the test easier: Try if yourself
HTML:
<input type="text" id="myTextBox" onkeyup="checkValue(this)" maxlength="10"></input>
<input id="sendButton" type="submit" value="SEND"></inpu
JAVASCRIPT:
function checkValue(textbox) {
if (textbox.value.length > 10) {
alert("TEXT TOO LONG");
document.getElementById("sendButton").disabled = true;
}
else
document.getElementById("sendButton").disabled = false;
}
I'm new with JavaScript. Can someone give me an example how to delete an empty form element upon submit?
<form action='...' method='post' id='mySubmitForm'>
<input type='text' name='name'>
<input type='text' name='email'>
<input type='text' name='phoneNumber'>
<input type='submit' value='Save'>
</form>
Is there a easy way to check with JavaScript if the form is empty and delete it before submission if so?
There is a submit event that the browser throws before form submission that you can use.
reference: http://www.quirksmode.org/js/forms.html
Return false if you don't want the form to be submitted, true if you want it to happen. In the event, delete / add the extra inputs that you want accordingly.
function validate(formName)
{
var form = document.forms[formName];
//validate, and do stuff
//remove items that you want with a call like this
form.removeChild(document.getElementById(id));
form.submit();
}
If this is for validation, you should really be doing validation server side, not client side.
You would call this function like so:
<input type=BUTTON onClick="validate('myForm')"/>
You can use jQuery, which is probably the easiest way.
$(document).ready(function() {
$('#.mySubmitForm').submit(function(event) {
event.preventDefault();
$('input[type=text]').each(function() {
var inputElement = $(this);
inputElement.val() == "" ? inputElement.remove() : null;
});
$(this).trigger('submit');
});
});
I didn't test that code, but it should delete the empty form values before submit, then remove them.
function onsubmit() {
[].forEach.call(document.querySelectorAll('#mySubmitForm input[type=text]'), function(col) {
if(col.value=='') col.disabled = 'disabled';
});
}
and onsubmit="onsubmit()" in your <form> tag
Checking through javaScript is easy, but I'd advise you to have-and-assign an id attribute to your form elements
You can check in the following way,
var email = document.getElementById('email').value;
and you can remove email from your form as shown below
form.removeChild(document.getElementById('email'));
form.submit();
you can have a look at Adding and Removing HTML elements dynamically with Javascript for more details.
I am a JavaScript newbie. I have an input text field that I wish to clear after pressing the form submit button. How would I do that?
In your FORM element, you need to override the onsubmit event with a JavaScript function and return true.
<script type="text/javascript">
function onFormSubmit ()
{
document.myform.someInput.value = "";
return true; // allow form submission to continue
}
</script>
<form name="myform" method="post" action="someaction.php" onsubmit="return onFormSubmit()">
<!-- form elements -->
</form>
If a user presses the submitbutton on a form the data will be submitted to the script given in the action attribute of the form. This means that the user navigates away from the site. After a refresh (assuming that the action of the form is the same as the source) the input field will be empty (given that it was empty in the first place).
If you are submitting the data through javascript and are not reloading the page, make sure that you execute Nick's code after you've submitted the data.
Hope this is clear (although I doubt it, my English is quite bad sometimes)..
function testSubmit()
{
var x = document.forms["myForm"]["input1"];
var y = document.forms["myForm"]["input2"];
if (x.value === "")
{
alert('plz fill!!');
return false;
}
if(y.value === "")
{
alert('plz fill the!!');
return false;
}
return true;
}
function submitForm()
{
if (testSubmit())
{
document.forms["myForm"].submit(); //first submit
document.forms["myForm"].reset(); //and then reset the form values
}
}
First Name: <input type="text" name="input1"/>
<br/>
Last Name: <input type="text" name="input2"/>
<br/>
<input type="button" value="Submit" onclick="submitForm()"/>
</form>
After successfully submitting or updating form or password you can put empty value.
CurrentPasswordcontroller.state.confirmPassword = '';