XSS又称CSS，全称Cross SiteScript，跨站脚本攻击，是Web程序中常见的漏洞，XSS属于被动式且用于客户端的攻击方式，所以容易被忽略其危害性。其原理是攻击者向有XSS漏洞的网站中输入(传入)恶意的HTML代码，当其它用户浏览该网站时，这段HTML代码会自动执行，从而达到攻击的目的。如，盗取用户Cookie、破坏页面结构、重定向到其它网站等。

这是我从别的PHP框架中扒的一段，重新整理成js的版本。如果对你有点用，就点个赞呗～

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{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{0,8}([9][10][13]);?)?';
                        pattern += ')?';
                    }
                    pattern += ra[i][j];
                }
                parttern = new RegExp(pattern,'gi');
                var replacement = ra[i].substr(0, 2) + '<x>'+ ra[i].substr(2);
                val = val.replace(parttern, replacement);
                if (val_before  == val) {
                    found = false;
                }
            }
        }
        return val;
    }