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How to prevent form from being submitted?

I have a form that has a submit button in it somewhere.

However, I would like to somehow 'catch' the submit event and prevent it from occurring.

Is there some way I can do this?

I can't modify the submit button, because it's part of a custom control.

You could still access the submit button. Render the page and grab its ClientID by viewing the page source. Then, using something like jQuery you could do something like $('#ctl01_cph01_controlBtn1').click(function() {return false;});
@Rafael: True... but that would be a last resort - this is a very complex control.
@Raf that's asp.net based, and also not a best practice. But its essentially correct. I'd just avoid peeking at the source and using the control name, as it may change if someone edits the page. Unintended side effects and such.

S
Saabbir

Unlike the other answers, return false is only part of the answer. Consider the scenario in which a JS error occurs prior to the return statement...

html

<form onsubmit="return mySubmitFunction(event)">
  ...
</form>

script

function mySubmitFunction()
{
  someBug()
  return false;
}

returning false here won't be executed and the form will be submitted either way. You should also call preventDefault to prevent the default form action for Ajax form submissions.

function mySubmitFunction(e) {
  e.preventDefault();
  someBug();
  return false;
}

In this case, even with the bug the form won't submit!

Alternatively, a try...catch block could be used.

function mySubmit(e) { 
  e.preventDefault(); 
  try {
   someBug();
  } catch (e) {
   throw new Error(e.message);
  }
  return false;
}

Why not return false directly from onsumbit?
You might want to show an error message to the user in the onsubmit. Fore example, "complete this mandatory field then submit". In that case event.preventDefault will come in very handy
worked ... had to use the word event in brackets in firefox
@BenRowe You Should add evt parameter to the called method. (<form onsubmit="return mySubmitFunction(evt)">) .Otherwise it gives Undefined error.
I had to use the exact word event as parameter in Chrome, just if anyone's struggling with this..
9
9 revs, 3 users 73%

You can use inline event onsubmit like this

<form onsubmit="alert('stop submit'); return false;" >

Or

<script>
   function toSubmit(){
      alert('I will not submit');
      return false;
   }
</script>

<form onsubmit="return toSubmit();" >

Demo

Now, this may be not a good idea when making big projects. You may need to use Event Listeners.

Please read more about Inline Events vs Event Listeners (addEventListener and IE's attachEvent) here. For I can not explain it more than Chris Baker did.

Both are correct, but none of them are "best" per se, and there may be a reason the developer chose to use both approaches.


Nice, quickly solution on the road.
for some reason, <form onsubmit="return false;" > does not work for me.
M
Michał Perłakowski

Attach an event listener to the form using .addEventListener() and then call the .preventDefault() method on event:

const element = document.querySelector('form'); element.addEventListener('submit', event => { event.preventDefault(); // actual logic, e.g. validate the form console.log('Form submission cancelled.'); });

I think it's a better solution than defining a submit event handler inline with the onsubmit attribute because it separates webpage logic and structure. It's much easier to maintain a project where logic is separated from HTML. See: Unobtrusive JavaScript.

Using the .onsubmit property of the form DOM object is not a good idea because it prevents you from attaching multiple submit callbacks to one element. See addEventListener vs onclick .


& for jquery: $("button").click(function(e) { e.preventDefault() });
+1 dunno why all the other answers keep using inline onsubmits, since OP mentioned he can't change button (which means he probably can't change form either). Wondering if there's a way to get the 'form' if we have the button id
Inline trash still the most voted, but thats not really the way of programming in JS since...2012? This Solution is THE solution.
I like most of this solution, but I avoid using querySelector because it returns the first element in the document matching the given selector. This can make your code break if a second form is later added earlier in the page, something that happens frequently, such as if you decide to later add a login form to the header, or even if an invisible or hidden form is added by a CMS module. (I've seen this happen on projects.) Using getElementById is more reliable because the ID must be unique, at least per DOM tree, according to HTML specifications, and validators will catch when it is not.
V
Vikram Pudi

The following works as of now (tested in chrome and firefox):

<form onsubmit="event.preventDefault(); return validateMyForm();">

where validateMyForm() is a function that returns false if validation fails. The key point is to use the name event. We cannot use for e.g. e.preventDefault()


onsubmit="return validateMyForm();" is enough but validateMyForm() should return true or false.
T
ThePierrasse

Try this one...

HTML Code

<form class="submit">
    <input type="text" name="text1"/>
    <input type="text" name="text2"/>
    <input type="submit" name="Submit" value="submit"/>
</form>

jQuery Code

$(function(){
    $('.submit').on('submit', function(event){
        event.preventDefault();
        alert("Form Submission stopped.");
    });
});

or

$(function(){
    $('.submit').on('submit', function(event){
       event.preventDefault();
       event.stopPropagation();
       alert("Form Submission prevented / stopped.");
    });
});

There is no jQuery tag in this question.
@Gothdo and yet the solution is still the same. crazy right?
@Gothdo yea, it's exactly the same. eventObject.preventDefault. The way you bind the handler doesn't change the solution. I would even argue your answer is no different than the accepted one.
stopPropagation was the only thing that worked in my case. thanks! :)
n
naikus
var form = document.getElementById("idOfForm");
form.onsubmit = function() {
  return false;
}

I think that using .onsubmit is a bad idea because it prevents you from attaching multiple submit callbacks to one element. I recommend using .addEventListener().
Even if you have set an event handler via the property .onsubmit, you can still add additional handlers via .addEventListener(). The handler registered by the property will be invoked first then the ones registered with .addEventListener() in the order in which they were registered.
L
Lakhwinder Singh

For prevent form from submittion you only need to do this.

<form onsubmit="event.preventDefault()">
    .....
</form>

By using above code this will prevent your form submittion.


d
de-russification

To follow unobtrusive JavaScript programming conventions, and depending on how quickly the DOM will load, it may be a good idea to use the following:

<form onsubmit="return false;"></form>

Then wire up events using the onload or DOM ready if you're using a library.

$(function() { var $form = $('#my-form'); $form.removeAttr('onsubmit'); $form.submit(function(ev) { // quick validation example... $form.children('input[type="text"]').each(function(){ if($(this).val().length == 0) { alert('You are missing a field'); ev.preventDefault(); } }); }); }); label { display: block; } #my-form > input[type="text"] { background: cyan; }


Also, I would always use the action attribute as some people may have some plugin like NoScript running which would then break the validation. If you're using the action attribute, at the very least your user will get redirected by the server based on the backend validation. If you're using something like window.location, on the other hand, things will be bad.


H
Hasan A Yousef

You can add eventListner to the form, that preventDefault() and convert form data to JSON as below:

const formToJSON = elements => [].reduce.call(elements, (data, element) => { data[element.name] = element.value; return data; }, {}); const handleFormSubmit = event => { event.preventDefault(); const data = formToJSON(form.elements); console.log(data); // const odata = JSON.stringify(data, null, " "); const jdata = JSON.stringify(data); console.log(jdata); (async () => { const rawResponse = await fetch('/', { method: 'POST', headers: { 'Accept': 'application/json', 'Content-Type': 'application/json' }, body: jdata }); const content = await rawResponse.json(); console.log(content); })(); }; const form = document.forms['myForm']; form.addEventListener('submit', handleFormSubmit);
















d
devugur
<form v-on:submit.prevent="yourMethodHere">

The submit event will no longer reload the page. It runs your method.

From vue documentation: https://vuejs.org/guide/essentials/event-handling.html#event-modifiers


Please read How do I write a good answer?. While this code block may answer the OP's question, this answer would be much more useful if you explain how this code is different from the code in the question, what you've changed, why you've changed it and why that solves the problem without introducing others.
y
yozawiratama

Here my answer :

<form onsubmit="event.preventDefault();searchOrder(event);">
...
</form>
<script>
const searchOrder = e => {
    e.preventDefault();
    const name = e.target.name.value;
    renderSearching();

    return false;
}
</script>

I add event.preventDefault(); on onsubmit and it works.