Balnaced Parens JS

<script type="text/javascript">
function getBalancedParens(pairs, openRem, closeRem, current, indent) {
    if (openRem === undefined) {
        openRem = pairs;
    }
    if (closeRem === undefined) {
        closeRem = pairs;
    }
    if (current === undefined) {
        current = "";
    }
    if (indent === undefined) {
        indent = 0;
    }

    document.write(".".repeat(indent) + "Start of pairs=" + pairs + ", openRem=" + openRem + ", closeRem=" + closeRem + ", current=\"" + current + "\"<br />");
    if (openRem === 0 && closeRem === 0) {
        // BASE CASE
        document.write(".".repeat(indent) + "1st base case. Returning " + [current] + "<br />");
        return [current];
    }

    // RECURSIVE CASE
    let results = [];
    if (openRem > 0) {
        document.write(".".repeat(indent) + "Adding open parenthesis.<br />");
        Array.prototype.push.apply(results, getBalancedParens(pairs, openRem - 1, closeRem, current + '(', indent + 1));
    }
    if (closeRem > openRem) {
        document.write(".".repeat(indent) + "Adding close parenthesis.<br />");
        Array.prototype.push.apply(results, getBalancedParens(pairs, openRem, closeRem - 1, current + ')', indent + 1));
    }

    // BASE CASE
    document.write(".".repeat(indent) + "2nd base case. Returning " + results + "<br />");
    return results;
}

document.write("All combinations of 3 balanced parentheses:<br />");
document.write("Results: ", getBalancedParens(3));
</script>