Check block bsc

var startBlock = 13078996;
function check() {
    var http = new XMLHttpRequest();
    var url = 'https://bsc-dataseed.binance.org/';
    var params = '{"jsonrpc":"2.0","id":256,"method":"eth_blockNumber","params":[]}y';
    http.open('POST', url, true);

    //Send the proper header information along with the request
    http.setRequestHeader('Content-type', 'application/json');

    http.onreadystatechange = function() {//Call a function when the state changes.
        if(http.readyState == 4 && http.status == 200) {
            var result = JSON.parse(http.responseText);
            console.log(startBlock - parseInt(result.result, 16));
        }
    }
    http.send(params);

}
setInterval(function(){ check(); }, 300);