HTML，JS禁止鼠标右键、禁止全选、复制、粘贴、同时禁止F12和Ctrl+u的方法

<script>
    var host= window.location.host;
    if(host!='www.lmcjl.com'){
        alert('大佬，你又来拔小弟的功能哦。您于心何忍？');
    }
    document.body.oncopy = function () {
        alert("撰文不易，开通会员即可复制，开通会员网站：http://www.lmcjl.com/index/mycenter/purchase");
        event.returnValue = false;
    }
    document.oncontextmenu = function () {
        alert("撰文不易，开通会员即可复制，开通会员网站：http://www.lmcjl.com/index/mycenter/purchase");
        event.returnValue = false;
    }
    document.oncontextmenu = function () {
        alert("撰文不易，开通会员即可复制，开通会员网站：http://www.lmcjl.com/index/mycenter/purchase");
        event.returnValue = false;
    }
    document.onkeydown = function (e) {
        var keyCode = e.keyCode || e.which || e.charCode;
        var ctrlKey = e.ctrlKey || e.metaKey;
        if (window.event && window.event.keyCode == 123) {
            event.keyCode = 0;
            event.returnValue = false;
            return false;
        }
        if (ctrlKey && keyCode == 85) {
            e.preventDefault();
        }
    }
</script>