屏蔽浏览器退格键页面后退

 window.onload = function () {
    document.getElementsByTagName("body")[0].onkeydown = function (event) {
        if (event.keyCode == 8) {
            var elem = event.target || event.srcElement || event.currentTarget;
            var name = elem.nodeName;
            if (name != 'INPUT' && name != 'TEXTAREA') {
                console.info("1");
                return _stopIt(event);
            }
            var type_e = elem.type.toUpperCase();
            if (name == 'INPUT' && (type_e != 'TEXT' && type_e != 'TEXTAREA' && type_e != 'PASSWORD' && type_e != 'FILE' && type_e != 'EMAIL' && type_e != 'SEARCH')) {
                console.info("2");
                return _stopIt(event);
            }
            if (name == 'INPUT' && (elem.readOnly == true || elem.disabled == true)) {
                console.info("3");
                return _stopIt(event);
            }
        }
    };
};
function _stopIt(e) {
    if(e.returnValue) {
        e.returnValue = false ;
    }
    if(e.preventDefault){
        e.preventDefault();
    }
    return false;
}