SOURCE

function debug(msg){
        let log = document.getElementById("debuglog");
        if(!log){
            log = document.createElement("log")
            log.id = "debuglog"
            log.innerHTML = "<h1>debug log</h1>"
            document.body.appendChild(log)
        }
        let pre = document.createElement('pre')
        let text = document.createTextNode(msg)
        pre.appendChild(text)
        log.appendChild(pre)
    }
    let k = "holle";
    debug(k)