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const sanitize = (html, tags = undefined, attributes = undefined) => {
    var attributes = attributes || [
      { attribute: "src", tags: "*", regex: /^(?:https|http|\/\/):/ },
      { attribute: "href", tags: "*", regex: /^(?!javascript:).+/ },
      { attribute: "width", tags: "*", regex: /^[0-9]+$/ },
      { attribute: "height", tags: "*", regex: /^[0-9]+$/ },
      { attribute: "id", tags: "*", regex: /^[a-zA-Z]+$/ },
      { attribute: "class", tags: "*", regex: /^[a-zA-Z ]+$/ },
      { attribute: "value", tags: ["INPUT", "TEXTAREA"], regex: /^.+$/ },
      { attribute: "checked", tags: ["INPUT"], regex: /^(?:true|false)+$/ },
      {
        attribute: "placeholder",
        tags: ["INPUT", "TEXTAREA"],
        regex: /^.+$/,
      },
      {
        attribute: "alt",
        tags: ["IMG", "AREA", "INPUT"],
        //"^" and "$" match beggining and end
        regex: /^[0-9a-zA-Z]+$/,
      },
      { attribute: "autofocus", tags: ["INPUT"], regex: /^(?:true|false)+$/ },
      { attribute: "for", tags: ["LABEL", "OUTPUT"], regex: /^[a-zA-Z0-9]+$/ },
    ]
    var tags = tags || [
      "I",
      "P",
      "B",
      "BODY",
      "HTML",
      "DEL",
      "INS",
      "STRONG",
      "SMALL",
      "A",
      "IMG",
      "CITE",
      "FIGCAPTION",
      "ASIDE",
      "ARTICLE",
      "SUMMARY",
      "DETAILS",
      "NAV",
      "TD",
      "TH",
      "TABLE",
      "THEAD",
      "TBODY",
      "NAV",
      "SPAN",
      "BR",
      "CODE",
      "PRE",
      "BLOCKQUOTE",
      "EM",
      "HR",
      "H1",
      "H2",
      "H3",
      "H4",
      "H5",
      "H6",
      "DIV",
      "MAIN",
      "HEADER",
      "FOOTER",
      "SELECT",
      "COL",
      "AREA",
      "ADDRESS",
      "ABBR",
      "BDI",
      "BDO",
    ]

    attributes = attributes.map((el) => {
      if (typeof el === "string") {
        return { attribute: el, tags: "*", regex: /^.+$/ }
      }
      let output = el
      if (!el.hasOwnProperty("tags")) {
        output.tags = "*"
      }
      if (!el.hasOwnProperty("regex")) {
        output.regex = /^.+$/
      }
      return output
    })
    var el = new DOMParser().parseFromString(html, "text/html")
    var elements = el.querySelectorAll("*")
    for (let i = 0; i < elements.length; i++) {
      const current = elements[i]
      let attr_list = get_attributes(current)
      for (let j = 0; j < attr_list.length; j++) {
        const attribute = attr_list[j]
        if (!attribute_matches(current, attribute)) {
          current.removeAttribute(attr_list[j])
        }
      }
      if (!tags.includes(current.tagName)) {
        current.remove()
      }
    }
    return el.documentElement.innerHTML
    function attribute_matches(element, attribute) {
      let output = attributes.filter((attr) => {
        let returnval =
          attr.attribute === attribute &&
          (attr.tags === "*" || attr.tags.includes(element.tagName)) &&
          attr.regex.test(element.getAttribute(attribute))
        return returnval
      })

      return output.length > 0
    }
    function get_attributes(element) {
      for (
        var i = 0, atts = element.attributes, n = atts.length, arr = [];
        i < n;
        i++
      ) {
        arr.push(atts[i].nodeName)
      }
      return arr
    }
  }
star

Thu Dec 16 2021 22:52:07 GMT+0000 (UTC) https://stackoverflow.com/questions/295566/sanitize-rewrite-html-on-the-client-side/66028632

#javascript #html #sanitize #xss

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