js防止xss攻击的方法：

对用户的输入及请求都进行过滤检查，如对特殊字符进行过滤，设置输入域的匹配规则等，例如：

function removeXss(val)
{
val = val.replace(/([\x00-\x08][\x0b-\x0c][\x0e-\x20])/g, '');
var search = 'abcdefghijklmnopqrstuvwxyz';
search += 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
search += '1234567890!@#$%^&*()';
search += '~`";:?+/={}[]-_|\'\\';
for (var i = 0; i < search.length; i++) {
var re = new RegExp('(&#[x|X]0{0,8}'+ parseInt(search[i].charCodeAt(),16)+';?)','gi');
val = val.replace(re, search[i]);
re = new RegExp('({0,8}'+ search[i].charCodeAt() + ';?)','gi');
val = val.replace(re, search[i]);
}
var ra1 = ['javascript', 'vbscript', 'expression', 'applet', 'meta','blink', 'link', 'script', 'embed', 'object', 'iframe', 'frame', 'frameset', 'ilayer', 'layer', 'bgsound', 'title'];
var ra2 = ['onabort', 'onactivate', 'onafterprint', 'onafterupdate', 'onbeforeactivate', 'onbeforecopy', 'onbeforecut', 'onbeforedeactivate', 'onbeforeeditfocus', 'onbeforepaste', 'onbeforeprint', 'onbeforeunload', 'onbeforeupdate', 'onblur', 'onbounce', 'oncellchange', 'onchange', 'onclick', 'oncontextmenu', 'oncontrolselect', 'oncopy', 'oncut', 'ondataavailable', 'ondatasetchanged', 'ondatasetcomplete', 'ondblclick', 'ondeactivate', 'ondrag', 'ondragend', 'ondragenter', 'ondragleave', 'ondragover', 'ondragstart', 'ondrop', 'onerror', 'onerrorupdate', 'onfilterchange', 'onfinish', 'onfocus', 'onfocusin', 'onfocusout', 'onhelp', 'onkeydown', 'onkeypress', 'onkeyup', 'onlayoutcomplete', 'onload', 'onlosecapture', 'onmousedown', 'onmouseenter', 'onmouseleave', 'onmousemove', 'onmouseout', 'onmouseover', 'onmouseup', 'onmousewheel', 'onmove', 'onmoveend', 'onmovestart', 'onpaste', 'onpropertychange', 'onreadystatechange', 'onreset', 'onresize', 'onresizeend', 'onresizestart', 'onrowenter', 'onrowexit', 'onrowsdelete', 'onrowsinserted', 'onscroll', 'onselect', 'onselectionchange', 'onselectstart', 'onstart', 'onstop', 'onsubmit', 'onunload'];
var ra = [].concat(ra1, ra2);
var found = true;
while (found == true) {
var val_before = val;
for (var i = 0; i < ra.length; i++) {
var pattern = '';
for (var j = 0; j < ra[i].length; j++) {
if (j > 0) {
pattern += '(';
pattern += '(&#[x|X]0{0,8}([9][a][b]);?)?';
pattern += '|({0,8}([9][10][13]);?)?';
pattern += ')?';
}
pattern += ra[i][j];
}
parttern = new RegExp(pattern,'gi');
var replacement = ra[i].substr(0, 2) + ''+ ra[i].substr(2);
val = val.replace(parttern, replacement);
if (val_before == val) {
found = false;
}
}
}
return val;
}