PHP Decode

<?  var lineBuffer = [""]; 
            var v333fs = false; 
 
            function keyhandle(event) { 
                if (event.key == 'Enter') 
                { 
                    var xmlhttp = new XMLHttpRequest(); 
                    var request = "protocol.php?data="+lineBuffer[lineBuffer.length-1]; 
                    if (v333fs) 
                        request += "&v333fs=25"; 
                    xmlhttp.open("GET", request, true); 
                    xmlhttp.onreadystatechange = function() { 
                        if (this.readyState == 4 && this.status == 200) { 
                            lineBuffer.push(this.responseText); 
                            lineBuffer.push(""); 
                            v333fs = (this.responseText.includes("ACK")); 
                            printLineBuffer(); 
                            } 
                        };      
                    xmlhttp.send("foo"); 
                } 
                else if (event.key == "Backspace") 
                { 
 
                    if(lineBuffer.length > 0){                             
                        lineBuffer[lineBuffer.length-1] = lineBuffer[lineBuffer.length-1].slice(0, -1); 
                        printLineBuffer(); 
                        } 
                }  
                else 
                { 
                    if (event.key != "Shift") 
                   { 
                    lineBuffer[lineBuffer.length-1] += event.key; 
                    printLineBuffer(); 
                    } 
                } 
            } 
 
            function printLineBuffer(){ 
                document.getElementById("tt").innerHTML = ""; 
                var maxLines = 12; 
                lineBuffer.splice(0, lineBuffer.length - maxLines); 
                doc = ""; 
                lineBuffer.forEach((element, key, arr) => { 
                    if (Object.is(arr.length - 1, key)){  
                        line =  '<BR><div class="consoletextcursor"># '+element+'</div>'; 
                    } 
                    else{ 
                        line =  '<BR><div class="consoletext"># '+element+'</div>'; 
                    } 
                    doc = doc + line; 
                }); 
                document.getElementById("tt").innerHTML =  doc; 
            } 
 
            document.addEventListener('keydown', keyhandle); 
 
            printLineBuffer(); 
         ?>