const regex = /(?<=(?<![<](?:pre|code)[^>]*?)[>])(?:[\s\n]*([^<]*?)[\s\n]*)(?=[<](?![\/](?:pre|code)))/dig;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('(?<=(?<![<](?:pre|code)[^>]*?)[>])(?:[\\s\\n]*([^<]*?)[\\s\\n]*)(?=[<](?![\\\/](?:pre|code)))', 'dig')
const str = `<testing>
LMAO
</testing>
<code> this should be untouched</code>
<strong>
but this block should be sanitized
</strong>
<b>lol</b>
<b>
oooo
</b>`;
const subst = `$1`;
// 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