const regex = /^(?:(“(?! “).*?)\s*”|(“) “(.*)|((?!“).*?)\s*”)$/gm;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('^(?:(“(?! “).*?)\\s*”|(“) “(.*)|((?!“).*?)\\s*”)$', 'gm')
const str = `“ Criteria 1, ending with RD and beginning with LD, but not LDLD, remove RD ”
“ “ Criteria 1, ending with RD but beginning with LDLD, do nothing to RD ”
“ “ Criteria 2, beginning with LDLD, make it begin with LD ”
Criteria 3 with non-matching RD, remove RD ”`;
const subst = `$1$2$3$4`;
// The substituted value will be contained in the result variable
const result = str.replace(regex, subst);
console.log('Substitution result: ', result);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for JavaScript, please visit: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions