Template literal for multiline regex with comments

regex-template-literal.js

/**
 * Simple custom template literal that removes comments and whitespace in regex
 */
const regex = ({ raw }, ...substitutions) =>
    new RegExp(
        String.raw(
            { raw: raw.map(v => v.replace(/\s+#.*$/gm, '').replace(/[\s\r\n]+/g, '')) },
            ...substitutions,
        ),
    );

/**
 * Example: detect import syntax in text
 */
const detectImport = filename => 
    regex`
        import
        [\s\r\n]+                       # whitespace (possibly newline)
        (?:                             # optional uncaptured
            ([\w$]+)                    # capture $1: default import
            [\s\r\n]*                   # optional whitespace (possibly newline)
        )?
        (?:                             # optional uncaptured
            ,
            [\s\r\n]*                   # optional whitespace (possibly newline)
        )?                              
        (?:                             # optional uncaptured
            {
            ([^}]*)                     # capture $2: named imports text (anything but closing brace)
            }
            [\s\r\n]*                   # optional whitespace (possibly newline)
        )?
        from
        [\s\r\n]+                       # whitespace (possibly newline)
        '[^']+/${filename}(?:\.js)?'    # single quoted module specifier ending in given filename
        `,

Support for flags:

var { re } = (()=>{
  const reComments = /\s+#.*$/gm;
  const reWhitespace = /[\s\r\n]+/g;
  const reFlags = /^[dgimsuvy]+$/;
  const reEscape = /[-\\^$*+?.()|[\]{}]/g;
  function re(strings, ...values) {
    let flags = '';
    if (strings[0] === '' && reFlags.test(values[0])) {
      strings = strings.slice(1);
      flags = values.shift();  
    }
    values = values.map(x=> {
      return Array.isArray(x) 
        ? `(?:${x.map(y=>y.toString().replace(reEscape, '\\$&')).join('|')})` 
        : x.toString().replace(reEscape, '\\$&')
    });
    const raw = strings.map(v => v.replace(reComments, '').replace(reWhitespace, ''))
    const str = String.raw({ raw }, ...values);
    const rgx = new RegExp(str, flags);
    return rgx;
  };
  return { re };
})();

const filename = "/c/my/test/file.js";
re`${'igm'}
      import
      [\s\r\n]+                       # whitespace (possibly newline)
      (?:                             # optional uncaptured
          ([\w$]+)                    # capture $1: default import
          [\s\r\n]*                   # optional whitespace (possibly newline)
      )?
      (?:                             # optional uncaptured
          ,
          [\s\r\n]*                   # optional whitespace (possibly newline)
      )?                              
      (?:                             # optional uncaptured
          {
          ([^}]*)                     # capture $2: named imports text (anything but closing brace)
          }
          [\s\r\n]*                   # optional whitespace (possibly newline)
      )?
      from
      [\s\r\n]+                       # whitespace (possibly newline)
      '[^']+/${filename}(?:\.js)?'    # single quoted module specifier ending in given filename
    `;

=> /import[s]+(?:([w$]+)[s]*)?(?:,[s]*)?(?:{([^}]*)}[s]*)?from[s]+'[^']+\/\/c\/my\/test\/file\.js(?:.js)?'/gim