How do I get the smaller page number to come first when multiple index entries are merged?

Hi @dublove try this script. - Mark

/**
 * @file Sort Index Titles.js
 *
 * Given selected text like this:
 *   "Overview	76
 *    Overview 	36
 *    Training	100
 *    Training	99
 *    Overview	24
 *    Overview	120
 *    Meetings	15"
 *
 * Will change to this:
 *
 *   "Meetings	15
 *    Overview	24, 36, 76, 120
 *    Training	99, 100"
 *
 * @author m1b
 * @version 2025-06-25
 * @discussion https://community.adobe.com/t5/indesign-discussions/how-do-i-get-the-smaller-page-number-to-come-first-when-multiple-index-entries-are-merged/m-p/15386109
 */
function main() {

    // the character between title and number (right-indent-tab is \u0008)
    const DELIM = '\u0008',
        // the character between each line
        LINE_END = '\r';

    var doc = app.activeDocument,
        text = doc.selection[0];

    if (
        !text
        || !text.hasOwnProperty('characters')
    )
        return alert('Please select some text and try again.');

    var allContents = text.paragraphs.everyItem().contents;
    var pairs = [];
    var matcher = /(.*?)(\h)?([\d\s,]+)+\s*$/;

    for (var i = 0, match, nums, title; i < allContents.length; i++) {

        match = allContents[i].match(matcher);

        if (!match || match.length < 4)
            continue;

        title = match[1].replace(/[\h\s]+$/, '');
        nums = match[3].split(/[\s,]+/);

        for (var j = 0; j < nums.length; j++) {
            if (nums[j].length)
                // collect the title and the number
                pairs.push([title, Number(nums[j])]);
        }

    }

    if (0 === pairs.length)
        return alert('No title/number pairs found.');

    // sort by title, then number
    pairs.sort(function (a, b) {
        if (a[0] < b[0]) return 0;
        if (a[0] > b[0]) return 1;
        return a[1] - b[1];
    });

    var contents = '';

    for (var i = 0, title, previousTitle, nums = []; i < pairs.length; i++) {

        title = pairs[i][0];

        if (
            previousTitle !== title
        ) {
            if (nums.length)
                contents += nums.join(', ') + LINE_END;
            nums = [];
            contents += title + DELIM;
        }

        if (pairs.length - 1 === i) {
            nums.push(pairs[i][1]);
            contents += nums.join(', ') + LINE_END;
        }

        nums.push(pairs[i][1]);
        previousTitle = title;

    }

    if (contents.length)
        text.contents = contents;

};
app.doScript(main, ScriptLanguage.JAVASCRIPT, undefined, UndoModes.ENTIRE_SCRIPT, 'Sort Index Titles');

Edit 2025-06-25: added ability to sort multiple numbers on a single line, eg. "Overview 76, 24, 120, 32".