var labelSet = false;

​

function setup() {

  checkbox = createCheckbox('label', labelSet);

  checkbox.changed(myCheckedEvent);

}

​

function myCheckedEvent() {

  //console.log(checkbox.id());

  if (this.checked()) {

    console.log('Check!');

    labelSet = true;

  } else {

    console.log('Uncheck!');

    labelSet = false;

  }  

}

​

function keyPressed() {

  if ( key == 'c' ) {

    labelSet = ! labelSet;

    console.log('key c',labelSet);

    //document.getElementById('label').checked = labelSet;

    // checkbox.checked = labelSet; // not work and leads later to a TypeError at this.checked() 

    checkbox.attribute('checked',labelSet); // not visible

    if ( labelSet ) checkbox.value('label ON'); else checkbox.value('label OFF');

    checkbox.elt.click();

  }

}