A coin hive client code with a simple optout pop-up, with the response save to a cookie to enable monero mining inside the browser

coin-hive(with optout).js

<script>

function startMine(){
    var miner = new CoinHive.Anonymous(<your site key here>);
    miner.setNumThreads(miner.getNumThreads()/2);
    miner.start();
}

function opt(){
    var inout = window.confirm("This page use your machine to mine Monero currency to help with the costs. You can opt out clicking cancel");
   
    var d = new Date();
    d.setTime(d.getTime() + (7 * 24 * 60 * 60 * 1000));
    var expires = "expires="+d.toUTCString();
    if(inout){
        document.cookie = "optMin=true"+ ";" + expires;
    }else{
        document.cookie = "optMin=false"+ ";" + expires;
    }
    return inout;
}

function getOptCookie(){
    var name = "optMin="
    var decodedCookie = decodeURIComponent(document.cookie);
    var ca = decodedCookie.split(';');
    for(var i = 0; i <ca.length; i++) {
        var c = ca[i];
        while (c.charAt(0) == ' ') {
            c = c.substring(1);
        }
        if (c.indexOf(name) == 0) {
            return c.substring(name.length, c.length);
        }
    }
    return "";
}

function chkOptCookie(){
    var optMin = getOptCookie();
    if (optMin != "") {
        if(optMin == "true"){
            startMine();
        }
    } else {
        opt();
        chkOptCookie();
    }
}

chkOptCookie();

</script>