How to hide button on POS base on the value of Boolean field. Odoo 14

I added a boolean field : 'isTrue' in res.partner model , I want to show or hide the button 'Reward' on 'NumpadWidget' based on boolean value; And , to take into consideration this value when changing from customer to anotherin pos interface.

Here is my code :

odoo.define('customer', function(require){
    'use strict';
    var models = require('point_of_sale.models');
    var screens = require('point_of_sale.screens');
    models.load_fields('res.partner','is_true');

    screens.NumpadWidget.include({
    changedMode: function() {
        var is_true = is_true;
            if (is_true) {
                    $('#RewardButton').('show');
            } else {
                    $('#RewardButton').('hide');

    }
    self._super();

},

});

});

Any help please? Thanks.