Regex to replace special characters with escape sequence in XML string

Question

I have a XML string which contains some special characters(<,>,&) in it and hence can not be parsed by using jQuery $.parseXML.

This is the sample XML string



  
    ab<
    
      
        {StateJob}
        {AnnualSalary}
      
    
    
      
        {FirstName}
        {MiddleName}
        {LastName}
        {Generation}
      
      {Email}
      
        {SSN}
        {DateOfBirth}
      
      {Aliases}
      {PostalAddress}
    
    
      {Screenings}
      
        {Search&Type}
      
      
        yes
      
      
        true
      
      
        Sample XML
      
      
        {CallbackURL}
      
      {AdditionalItems}
    
    {Documentation}

Note the value of tag ReferenceId on 4th line, it contains special character and hence this string can not be parsed to XML.

What I need is to replace those special characters with escape sequences(<,>,&). The closest I came across is this

how to escape xml entities in javascript?

But this answer assumes that we have XML node values already with us.

My requirements is different, I have the complete xml as a string and I want to replace only the node values without touching the tag names(tags also contain <,>).

This is what i tried using jQuery

$(xml).each(function() {
            var t = $(this).wrap('').parent().html();

            t.replace(/&/g, '&')
                   .replace(//g, '>')
                   .replace(/"/g, '"')
                   .replace(/'/g, ''');
            xml = t;
        });

This is working fine, the only problem with this code is that it is converting the XML tags to lower case. I thing this is because of jQuery's behavior.

Please suggest be a fix/solution for this.Thanks

Vishal Dubey · Accepted Answer

I finally achieved what i needed. Thanks to @mplungjan. As he also pointed out, an XML file must be valid to get parsed and making it valid should be done where the XML is created.

My scenario was somewhat different. I HAD TO fix the invalid XML string in javascript only, before i could parse it.

I had to apply a dirty hack to achive it. While parsing the XML string in javascript(or any other programming language), we get an error specifying whats wrong AND the line number. What i did was this

Retrieve the line number from error.
Extract that line from the string and fix it.
Repeat the process till the complete XML is fixed.

Here's what i did

var oParser = new DOMParser();

        function escapeRegExp(str) {
          return str.replace(/[\-/\{\}\*\+\?\.\\^\$\|]/g, "\$&");
        }

        function remove_error(str, line) {
            var allTexts = str.split("\n");
            var illegal = allTexts[line - 1];
            var extract = illegal.match(/>(.*)/g, '>')
               .replace(/"/g, '"')
               .replace(/'/g, ''');

            fix_extract = fix_extract.trim();console.log(fix_extract);
            var re = new RegExp(">"+escapeRegExp(extract.trim())+"<");
            str = str.replace(re,">"+fix_extract+"<");
            return str;
        }

        var fixed = "", final_fixed = "";

        function process(orig_str) {
            var newDOM = oParser.parseFromString(orig_str, "text/xml");
            var error = newDOM.getElementsByTagName("parsererror");

            if (error && error.length) {
                if (error[0] && error[0].innerHTML) {
                    var err_html = error[0].innerHTML;
                    var parse_err = oParser.parseFromString(err_html, "text/html");
                    var err_log = parse_err.getElementsByTagName("div")[0].innerHTML;
                    console.log(err_log);
                    //var string = err_log.substring(err_log.lastIndexOf("line")+1, err_log.lastIndexOf("at"));
                    var regex = /line\s*(.*?)\s*at/g;

                    var matches = [];
                    while (m = regex.exec(err_log)) {
                      matches.push(m[1]);
                    }console.log(matches);
                    var err_line = matches[0];
                    fixed = remove_error(orig_str, err_line);
                    if (fixed) {console.log(fixed);//return;
                        process(fixed);
                    }
                    //console.log(fixed);
                    //alert('Invalid XML:' + err_log);
                } else {
                    alert('XML could not be parsed');
                    return;
                }
                $('.welcome-page section.welcome .inner').html("Invalid XML");
            } else {
                final_fixed = orig_str;
            }

            if(final_fixed) {
                return final_fixed;
            }
        }
var newDOM = process(res[0][0]);

        if (!newDOM) {
            alert('XML could not be parsed');
            return;
        }

I know what i did is just a hack. But i didn't have any other options.

PS- Any edits to this answer are welcome.

Regex to replace special characters with escape sequence in XML string

Answers (2)

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