MooTools form set (text, radio, checkbox, select, radio)

text

$$('#form input[name=firstname]').set('value','Mike');

radio

$$('#form input[name=sex]')[1].set('checked',true);

checkbox

$$('#form input[name=relationship[]]').set('checked',false); /*reset*/
$$('#form input[name=relationship[]]')[2].set('checked',true);

select

$$('#form select[name=figure]').set('value', 6); 

textarea

$$('#form textarea[name=presenwords]').set('value','text');