const regex = /\(([1-9][\d\-\s,]*[0-9])\)/g;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('\\(([1-9][\\d\\-\\s,]*[0-9])\\)', 'g')
const str = `Headaches, intracranial hypertension, papilledema and exophthalmos may occur with intracranial infiltration.(7-15, 8)
(234---345)`;
const subst = `<span class="ref">$1</span>`;
// 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