Change default string on a textfiield triggered by button

1

my code goes like this.

frappe.ui.form.on(‘Patient’, {
refresh: function(frm) {

  frm.add_custom_button(('Action 1'), function(){
    patient_name.defaults() = 'Name1'
}, __("action"));
frm.add_custom_button(('Action 2'), function(){
    patient_name.defaults() = 'Name2'
}, __("action"));

}
});

Is it possible to autofill a textfield? or any suggestions, please?