How to unescape JavaScript string literal value?

Question

I am using regex to parse javascript code (using an ES parser, such as Esprima, is not an option for technical environment limitations).

The subject code (the code being parsed is):

(function() {
    $('#3bf779cd').replaceWith("<div class=\'shows\'>\n<\/div>");

    window.fadeItems();
}).call(this);

The value I am interested in is the first parameter of replaceWith , which is a string literal. I am getting this variable using regex:

const subjectValue = subjectCode.match(/\.replaceWith\(((["'])(?:(?=(\\?))\3.)*?\2)/m)[1].slice(1, -1);

console.log(subjectValue);

The output of this is:

<div class=\'shows\'>\n<\/div>

How do I escape subjectValue in a way that the output would be:

<div class='shows'>
</div>

Simply using unescape has no effect.

If I am not mistaken, the question comes does to how to unescape this value:

console.log('"<div class=\\\'shows\\\'>\\\\n<\\\/div>"');

Answer 1

You're looking for eval (yes you heard correctly):

 text = document.querySelector('script').textContent; dqString = /"(\\\\.|[^"])*"/g s = text.match(dqString)[0] raw = eval(s); alert(raw); 

 <script> (function() { $('#3bf779cd').replaceWith("<div class=\\'shows\\'>\\n<\\/div>"); window.fadeItems(); }); </script> 

Answer 2

The most idiotic way would be.

"<div class=\\'shows\\'>\\\\n<\\/div>".replace(/\\n/g, '').replace(/\\/g, '');
// "<div class='shows'></div>"

Smarter way would be to first unescape \\n's than check with regex if there are unescaped matches, and than escape those as well.