const regex = /^(wp/gm;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('^(wp', 'gm')
const str = `<wp:postmeta>
<wp:meta_key><![CDATA[meta_business_name]]></wp:meta_key>
<wp:meta_value><![CDATA[The Middle Spoon Desserterie & Bar]]></wp:meta_value>
</wp:postmeta>`;
const subst = `$1/$2`;
// 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