Hide field based on checkbox using javascript

I have two fields, field1 is a checkbox and field2 is a normal text field. I want to hide a field2 if a field1 is not checked and if

field1 is checked then show field2. For that, I am creating the following code:

odoo.define('survey_inherit.FormView', function (require) {
"use strict";

var FormView = require('web.FormView');
var core = require('web.core');
var QWeb = core.qweb;

var FormView = FormView.extend({
   _checkField: function(){

        var $checkbox = $('.custom-control-input').val();

        if ($checkbox.is(':checked')) {

        $('.o_form_label').show();
        $('.mandatory_msg_class').show();
        }else{

          $('.mandatory_msg_class').hide();
        }//close else
   },
});//close FormController

return FormView; 
});

But field2 is not hidden if field1 is not checked and also field2 is not shown if field1 is checked.