JQuery防止退格键网页后退的实现代码

$(document).keydown(function (e) { 
var doPrevent; 
if (e.keyCode == 8) { 
var d = e.srcElement || e.target; 
if (d.tagName.toUpperCase() == 'INPUT' || d.tagName.toUpperCase() == 'TEXTAREA') { 
doPrevent = d.readOnly || d.disabled; 
} 
else 
doPrevent = true; 
} 
else 
doPrevent = false; 

if (doPrevent) 
e.preventDefault(); 
});