const regex = /([\p{L}\p{N}_-]+)-\d+/gu;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('([\\p{L}\\p{N}_-]+)-\\d+', 'gu')
const str = `<if VERSION-1="A1" VERSION-17="A3">
<assign CTA="blue"></assign>
<assign CTA2="green"></assign>
<assign TEXT1="Hello%3Cbr/%3EWorld"></assign>
<elseif VERSION-147="A2">
<assign CTA="red"></assign>
<assign CTA2="yellow"></assign>
<assign CTA3="brown"></assign>
<assign TEXT1="Click%20%3Ca%20href='https://example.com'%20style='text-decoration:none;color:#000000;'%3Ehere%3C/a%3E"></assign>
</if>
// condition 2
<if VERSION-409="A4" VERSION-425="A5">
<assign CTA="purple"></assign>
<assign CTA2="orange"></assign>
<assign TEXT1="Hi%20%3Cspan%20style='font-%20weight:bold;'%3EJohn%3C/span%3E"></assign>
</if>
// condition 3
<if LANG-618="en_US">
<assign TITLE="English"></assign>
</if>`;
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