const regex = /(<p>|<div .*>)(\s*)(<a .*>)?(\s*)(<img .* \/>)(\s*)(<\/a>)?(\s*)(<p .*>.*<\/p>)?(\s*)(<\/p>|<\/div>)/;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('(<p>|<div .*>)(\\s*)(<a .*>)?(\\s*)(<img .* \\\/>)(\\s*)(<\\\/a>)?(\\s*)(<p .*>.*<\\\/p>)?(\\s*)(<\\\/p>|<\\\/div>)', '')
const str = `<div id="attachment_3340" style="width: 865px" class="wp-caption alignnone">
<img class="size-full wp-image-3340" alt="Testbild" src="https://beispiel.de/images/Testbild.jpg" width="855" height="631" />
<p class="wp-caption-text">© Copyright</p>
</div>`;
const subst = `$3$5$7$9`;
// 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