Clicking submit button of an HTML form by a Javascript code

Question

I don't know much about WEB probramming, so feel free to ask if I'm missing any details.

There is a certain website which I'm visiting very frequently, and it requires users to log in every time they visit. For the login page of this website, I'm trying to write down a userscript which will automatically log me in.

I managed to fill in the form fields, but don't have any idea how to click the submit button by JavaScript. The below is a condensed version of the original login code. How can I automatically click this submit button in this code?

<div id="start">
    <div id="header">
        <div id="login">
            <form id="loginForm" name="loginForm" method="post" action="#">
                // ...
                <input type="submit" id="loginSubmit" onclick="changeAction('submitInput','loginForm');document.forms['loginForm'].submit();" value="Log in" />
                // ...
            </form>
        </div>
    </div>
</div>

Answer 1

The usual way to submit a form in general is to call submit() on the form itself, as described in krtek's answer.

However, if you need to actually click a submit button for some reason (your code depends on the submit button's name/value being posted or something), you can click on the submit button itself like this:

document.getElementById('loginSubmit').click();