js验证url合法

var reg_=/^http:\/\/(?:[\w-\.]{0,255})(?:(?:\/?[^\s]{0,255}){0,255})/g;
var bb = reg_.test('http://image.baidu.com/i?tn=baiduimage&ct=201326592&cl=2&lm=-1&fr=&fmq=&pv=&ic=0&z=&se=1&showtab=0&fb=0&width=&height=&face=0&istype=2&word=%B9%F6%B6%AF%CC%F5+%CB%D8%B2%C4&s=0#pn=21');
alert(bb);//true