Contador

Para o codigo funcionar salve o arquivo como: contador.php <?php if (!file_exists("bd.txt")) { $arquivo = fopen("bd.txt", "a"); fwrite($arquivo, "0\n"); fclose($arquivo); } if (isset($_POST['salvar'])) { $arquivo = fopen("bd.txt", "a"); fwrite($arquivo, $_POST['salvar']." "); fclose($arquivo); } if (isset($_POST['quantidade'])) { $_POST['quantidade'] = (int) $_POST['quantidade']; $data[] = $_POST['quantidade']; $data[] = @end(file('bd.txt')); echo json_encode($data); exit; } echo '<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.1.0/jquery.min.js"></script>', 'Estamos em <span id="nmb">'.@end(file('bd.txt')). '</span>', '<br /><br />', 'Quantos deseja incluir? ', '<input type="number" id="numero">', '<input type="submit" id="add" value="ADD">', '<br /><br />', '<div id="teste" style="width: 100%; height: 300px; overflow: auto;">', '<ul></ul>', '</div>', '<script>', 'if ((localStorage.getItem(\'vl\')) && (localStorage.getItem(\'lv\'))) {', 'ir(parseInt(localStorage.getItem(\'vl\'))-1, parseInt(localStorage.getItem(\'lv\'))+1);', 'function ir(vl, lv) {', 'setTimeout(function() {', '$("#teste ul").append(\'<li>\' + lv + \'</li>\');', 'document.getElementById(\'teste\').scrollTop = 999999999999999;', '$("#nmb").text(lv); ', '$.ajax({', 'url: "contador.php",', 'method: "POST",', 'data: {', 'salvar: lv', '}', '});', 'if (vl > 1) {', 'ir(vl-1, lv+1);', '}', 'if (vl == 1) {', 'localStorage.removeItem(\'vl\');', 'localStorage.removeItem(\'lv\');', '}', 'else {', 'localStorage.setItem(\'vl\', vl); ', 'localStorage.setItem(\'lv\', lv);', '}', '}, 100);', '}', '}', '$("#add").click(function() {', '$.ajax({', 'url: "contador.php", ', 'method: "POST",', 'data: {', 'quantidade: $("#numero").val()', '},', 'success: function(data) {', 'data = JSON.parse(data); ', 'ir(data[0], parseInt(data[1])+1);', 'function ir(vl, lv) {', 'setTimeout(function() {', '$("#teste ul").append(\'<li>\' + lv + \'</li>\'); ', 'document.getElementById(\'teste\').scrollTop = 999999999999999;', '$("#nmb").text(lv);', '$.ajax({', 'url: "contador.php", ', 'method: "POST",', 'data: {', 'salvar: lv', '}', '});', 'if (vl > 1) {', 'ir(vl-1, lv+1);', '}', 'if (vl == 1) {', 'localStorage.removeItem(\'vl\');', 'localStorage.removeItem(\'lv\'); ', '}', 'else {', 'localStorage.setItem(\'vl\', vl);', 'localStorage.setItem(\'lv\', lv);', '}', '}, 100);', '}', '}', '});', '});', '</script>'; ?>