const regex = /<([\w\-\/]+)( +[\w\-]+(=(('[^']*')|("[^"]*")))?)* *>/g;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('<([\\w\\-\\\/]+)( +[\\w\\-]+(=((\'[^\']*\')|("[^"]*")))?)* *>', 'g')
const str = ` </div><!-- SectionHeaderWrapper --><div id="SectionContent"><h3 id="sAdministrativeDataSummary" class="mDisabled">Administrative data</h3><h3 id="sWorkersHazardViaInhalationRoute">Workers - Hazard via inhalation route</h3><h4>Systemic effects</h4><h5>Long term exposure</h5><dl class="HorDL"><dt>Hazard assessment conclusion:</dt><dd>no hazard identified</dd></dl></dl></dl></dl></dl></dl><h5>Acute/short term exposure</h5><dl class="HorDL"><dt>Hazard assessment conclusion:</dt><dd>no hazard identified</dd></dl><h6>DNEL related information</h6></dl></dl></dl></dl></dl><h4>Local effects</h4><h5>Long term exposure</h5><dl class="HorDL"><dt>Hazard assessment conclusion:</dt><dd>DNEL (Derived No Effect Level)
Value:</dt><dd><span class="UserEntry">0.02</span> mg/m³
Most sensitive endpoint:</dt><dd>repeated dose toxicity</dd></dl><h6>DNEL related information</h6><dl class="HorDL"><dt>DNEL derivation method:</dt><dd>other: <span class="UserEntry">Biocidal Products Regulation guidance for Human Health Risk Assessment (Volume III, Part B, December 2013</span>`;
const subst = `\n`;
// 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