javascript - JQM programatically RENAMING controlgroup's legend -

javascript - JQM programatically RENAMING controlgroup's legend -

i want rename programatically text of legend id=item_30

<fieldset data-role='controlgroup'> <legend id='item_30'>js</legend> <input id ='server1' type='radio' name='serveridor' value='1' onclick=definirserver('www.rotatorsurvey.com') ><label for='server1'>www.encuesta.ws</label> <input id ='server2' type='radio' name='serveridor' value='2' onclick=definirserver('www.rotatortablet.com') ><label for='server2'>www.onlinesurvey.co</label>

i tried:

document.getelementbyid('item_30').innerhtml = 'hello guys';

but chrome dramatically chash , says: uncaught typeerror: cannot set property 'innerhtml' of null

document.getelementbyid case-sensitive. alter to:

document.getelementbyid('item_30').innerhtml = 'hello guys';

javascript jquery jquery-mobile