Check or uncheck all check boxes using browser JavaScript console

checkboxes.js

# JS snippet for email notification settings, e. g. Twitter
cb=document.querySelectorAll('input[type="checkbox"]');for(i in cb){cb[i].checked=false}

# for Drupal 4.x comment approval form
cbx=document.getElementsByClassName('form-checkbox');for(i in cbx){cbx[i].checked=true}