Meteor Form Submission


Hello fellow Meteor developers. I am hoping a Meteor guru can please review my code below and verify if I am making proper use of return false and event.preventDefault(), especially in the context of form submission. The reason being, the Meteor docs use this approach:

// Prevent default form submit
return false;

While other tutorials use this approach:

event.preventDefault(); //prevent page reload

So I want to be sure that I am on the correct path before I proceed with the rest of my code.

Basically, my code gets the value of the username input and checks if the value exists in the database:


<template name="registration">
    <p class="message {{#if message_defined}}display_element{{/if}}">{{message}}</p>
    <form id="register_form">
        <input type="text" name="username" placeholder="username">


if (Meteor.isClient) {
    // This code only runs on the client


        message: function () {
            return Session.get("message");
        message_defined: function () {
            return Session.equals("message", undefined) ? false : true;
        "submit #register_form": function (event) {
            // This function is called when the registration form is submitted.

            event.preventDefault(); // Correct usage?

            var form_data = {

            if (!Match.test(form_data.username, String)) {
                Session.set("message", "username must be a string");
                return false;  // Correct usage?

            if (form_data.username.length < 6) {
                Session.set("message", "username must be at least 6 characters");
                return false;  // Correct usage?

  "check_username",form_data.username,function(error, result){
                if (error) {
                    Session.set("message", error);
                    return false;  // Correct usage?
                if (result) {
                    Session.set("message", result);
                    return false;  // Correct usage?

    check_username: function (username) {
        // If user exists, return error.

        var user = Meteor.users.findOne({username:username});
        if (user) {
            throw new Meteor.Error("username exists", "That username is already in use.");

        return "username not found";

if (Meteor.isServer) {
    Meteor.publish("users", function () {
        return Meteor.users.find();  // This publishes everything - be careful!


The differences are documented in the docs:

Prevents the action the browser would normally take in response to this event, such as following a link or submitting a form. Further handlers are still called, but cannot reverse the effect.


Returning false from a handler is the same as calling both stopImmediatePropagation and preventDefault on the event.


If it works for you then it should be fine. If you get any peculiar unintended behaviour you should read up on event bubbling and propagation to get a better understanding.


My response is going to be a bit controversial, but if you’re having problems with submit and event.preventDefault(), consider forgoing all that together, and submitting your form via a click event on a button instead. Because of how DDP and livedata and minimongo all work, the submit method is a bit… redundant? old-school? unnecessary?

I’ve worked on dozens of apps now and have never needed either submit or event.preventDefault() in them. $0.02


I disagree; submitting a form via a focused <input> (pressing enter on a computer keyboard or “send”-button on a smartphone’s keyboard) element is a nice feature. Of course this is capturable in JavaScript, but it requires extra work.

And what do a web crawlers think about inputs without forms?


TBH I haven’t used a “traditional” form submission for a couple of years now. I’ve used the on click method suggested by @awatson1978 (originally with AJAX, now with DDP).

I do think you may have a point regarding crawlers, but my forms are behind a login and invisible to those, anyway.