Change submit button text based on radio button selected

[HDFilmMaker2112]

I'm looking to change a submit buttons text based on which radio button is checked.

 

 

Here's the form data:

 

<div class="register_membership_type_position">
<span class="register_membership_type_title">Membership Type:</span>
<span class="register_membership_type_basic_position"><input type="radio" value="basic" name="register_membership_type" id="register_membership_type_basic" class="register_membership_type_basic" onchange="changeButton('basic');" checked="checked" /> <label for="register_membership_type_basic"><span class="register_radio_text">Basic</span></label></span>
<span class="register_membership_type_premium_position"><input type="radio" value="premium" name="register_membership_type" id="register_membership_type_premium" class="register_membership_type_premium" onchange="changeButton('premium');" /> <label for="register_membership_type_premium"><span class="register_radio_text">Premium</span></label></span>
<span class="register_membership_type_platinum_position"><input type="radio" value="platinum" name="register_membership_type" id="register_membership_type_platinum" class="register_membership_type_platinum" onchange="changeButton('platinum');" /> <label for="register_membership_type_platinum"><span class="register_radio_text">Platinum</span></label></span>
<span class="learn_more_position">(<a href="/signup?memberships">Learn More About Membership Types</a>)</span>
</div>

<p class="register_form_position register_submission">
<input type="submit" value="Sign Up" class="register_button_position" id="submit_button" />
</p>

 

 

Here's the javascript I've been trying, but haven't had much luck.

function changeButton(selection)
{
selection.charAt(0).toUpperCase() + selection.slice(1);
el = document.getElementById(submit_button);
el.value = 'Sign Up for '+selection+' Membership';
}

[PravinS]

Use this JS function

 

function changeButton(selection)
{
var t = selection.charAt(0).toUpperCase() + selection.slice(1);
el = document.getElementById('submit_button');
el.value = 'Sign Up for '+t+' Membership';
}

[HDFilmMaker2112]

Works perfectly, thanks.

 

Now is there anyway to make it so it loads "Sign Up for Basic Membership" right when the page loads?

 

I have the button set just to "Sign Up" for users without Javascript enabled.

 

Any way to use window.onload=changeButton(basic); (tried this and doesn't work) or something like that?

[PravinS]

put this at the end of the page

 

<script language="javascript" type="text/javascript">changeButton('basic');</script>

[HDFilmMaker2112]

put this at the end of the page

 

<script language="javascript" type="text/javascript">changeButton('basic');</script>

 

Excellent. Thanks.