How do I make checking a box automatically checks off several boxes?

hi, I'm working on a form with several check boxes. There is a section in particular that I would like it to auto check a box in this way:

When Checkbox A, B and C are checked Checkbox D would automatically check and when checkbox D is checked Checkbox A, B and C would also auto check.

i found this code online but its only working for ONE box, tried to make adjustments to it but its not working. Any help would be appreciated. Thanks

var v = event.target.value;

var f = this.getField("Checkboxb");

f.value = v;