JSFiddle - React, Tailwind, and code Playground

HTML

<select id="streets">
</select>
<select id="buildings">
</select>
<br/>
Укажите номер дома: <input type="text" id="_buildNum">
<button id="_btnCheck">Проверить</button>

JavaScript

var addresses = {
  "проспект Ленина": [1,2,3,4,5],
  "улица Пушкина" : [30,31,"32а"]
};

function in_array(needle, haystack, strict) {	
    // Checks if a value exists in an array
	// +   original by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
	var found = false, key, strict = !!strict;

	for (key in haystack) {
		if ((strict && haystack[key] === needle) || (!strict && haystack[key] == needle)) {
			found = true;
			break;
		}
	}
	return found;
}



$( document ).ready(function() {
  
  select = $('#streets');
  $('#streets').append('<option>Выберите улицу</option>');
  for (var street in addresses)
  {
    $('#streets').append('<option>'+street+'</option>');
  }
  
    $(document).on('change', '#streets', function(event){
        var street = $(this).val();
        $('#buildings').empty();
        addresses[street].forEach(function(v,i,a){
            $("#buildings").append('<option>'+v+'</option>')
        });
        
    });
    
    $(document).on('click', '#_btnCheck', function(event){
        var street = $('#streets').val();
        console.log(street);
        //всё приводим к нижнему регистру: 9А -> 9а
        var building = $('#_buildNum').val().toLowerCase();
        //уберём из строки все пробелы: 9 а -> 9а
        building = building.replace(/\s+/g, '');
        if(in_array( building, addresses[street]))
        {
            alert('подключен');
        }
        else
        {
            alert("не подключен");
        }        
    });
  
});