浏览器禁止右键菜单、禁止复制粘贴文档

<script>
    //屏蔽右键菜单
    document.oncontextmenu = function(event) {
        if (window.event) {
            event = window.event;
        }
        try {
            var the = event.srcElement;
            if (! ((the.tagName == "INPUT" && the.type.toLowerCase() == "text") || the.tagName == "TEXTAREA")) {
                return false;
            }
            return true;
        } catch(e) {
            return false;
        }
    }
    //屏蔽粘贴
    document.onpaste = function(event) {
        if (window.event) {
            event = window.event;
        }
        try {
            var the = event.srcElement;
            if (! ((the.tagName == "INPUT" && the.type.toLowerCase() == "text") || the.tagName == "TEXTAREA")) {
                return false;
            }
            return true;
        } catch(e) {
            return false;
        }
    }
    //屏蔽复制
    document.oncopy = function(event) {
        if (window.event) {
            event = window.event;
        }
        try {
            var the = event.srcElement;
            if (! ((the.tagName == "INPUT" && the.type.toLowerCase() == "text") || the.tagName == "TEXTAREA")) {
                return false;
            }
            return true;
        } catch(e) {
            return false;
        }
    }
    //屏蔽剪切
    document.oncut = function(event) {
        if (window.event) {
            event = window.event;
        }
        try {
            var the = event.srcElement;
            if (! ((the.tagName == "INPUT" && the.type.toLowerCase() == "text") || the.tagName == "TEXTAREA")) {
                return false;
            }
            return true;
        } catch(e) {
            return false;
        }
    }
    //屏蔽选中
    document.onselectstart = function(event) {
        if (window.event) {
            event = window.event;
        }
        try {
            var the = event.srcElement;
            if (! ((the.tagName == "INPUT" && the.type.toLowerCase() == "text") || the.tagName == "TEXTAREA")) {
                return false;
            }
            return true;
        } catch(e) {
            return false;
        }
    }
</script>