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// allow some attributes
var whiteListAttr = ['id', 'class', 'style'];
// allow link starts with '.', '/' and custom protocol with '://'
var linkRegex = /^([\w|-]+:\/\/)|^([\.|\/])+/;
// allow data uri, from https://gist.github.com/bgrins/6194623
var dataUriRegex = /^\s*data:([a-z]+\/[a-z0-9-+.]+(;[a-z-]+=[a-z0-9-]+)?)?(;base64)?,([a-z0-9!$&',()*+;=\-._~:@\/?%\s]*)\s*$/i;
// custom white list
var whiteList = filterXSS.whiteList;
// allow ol specify start number
whiteList['ol'] = ['start'];
// allow style tag
whiteList['style'] = [];
// allow kbd tag
whiteList['kbd'] = [];
// allow ifram tag with some safe attributes
whiteList['iframe'] = ['allowfullscreen', 'name', 'referrerpolicy', 'sandbox', 'src', 'srcdoc', 'width', 'height'];
var filterXSSOptions = {
allowCommentTag: true,
whiteList: whiteList,
escapeHtml: function (html) {
// allow html comment in multiple lines
return html.replace(/<(.*?)>/g, '<$1>');
},
onIgnoreTag: function (tag, html, options) {
// allow comment tag
if (tag == "!--") {
// do not filter its attributes
return html;
}
},
onTagAttr: function (tag, name, value, isWhiteAttr) {
// allow href and src that match linkRegex
if (isWhiteAttr && (name === 'href' || name === 'src') && linkRegex.test(value)) {
return name + '="' + filterXSS.escapeAttrValue(value) + '"';
}
// allow data uri in img src
if (isWhiteAttr && (tag == "img" && name === 'src') && dataUriRegex.test(value)) {
return name + '="' + filterXSS.escapeAttrValue(value) + '"';
}
},
onIgnoreTagAttr: function (tag, name, value, isWhiteAttr) {
// allow attr start with 'data-' or in the whiteListAttr
if (name.substr(0, 5) === 'data-' || whiteListAttr.indexOf(name) !== -1) {
// escape its value using built-in escapeAttrValue function
return name + '="' + filterXSS.escapeAttrValue(value) + '"';
}
}
};
function preventXSS(html) {
return filterXSS(html, filterXSSOptions);
}
module.exports = {
preventXSS: preventXSS
}
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