jsTree: Custom sort - Specify priority entries that must always be listed first, and the order they must appear

jstree-sort.js

// Example usage:
// $("#EstablishmentTree").jstree({
//     // other jstree properties ...
//     "sort": // function sort(a, b) { ... }
// });

function sort(a, b) {

    // For jsTree, use get_text() to get node text:
    // var textA = this.get_text(a), textB = this.get_text(b);
    var textA = a,
        textB = b;

    // Terms that should always be listed first, and the order they should appear
    var priorityTerms = ["This always comes first", "ZZZ alphabetically last, but still in priority list", "Alphabetically first, but third in priority list"];
    var indexOfTextA = priorityTerms.indexOf(textA),
        indexOfTextB = priorityTerms.indexOf(textB);

    return (indexOfTextA > -1 && indexOfTextB > -1) ? (indexOfTextA > indexOfTextB) ? 1 : -1
        : (indexOfTextA > -1) ? -1 : (indexOfTextB > -1) ? 1
        : (textA > textB) ? 1 : -1 // default alpha sort
}

// Uncomment for Jest testing
// module.exports = sort;

jstree-sort.test.js

/*
Jest tests: That custom sort(a,b) function in jstree-sort.js returns expected value

If first item comes before second item (when sorted alphanumerically)
then return -1,
else return 1

https://jestjs.io/
*/

const sort = require('./sort');

test.each([
    ["A", "Z", -1],
    ["Z", "A", 1],
    ["A", "This always comes first", 1],
    ["This always comes first", "A", -1],
    ["This always comes first", "Alphabetically first, but third in priority list", -1],
    ["ZZZ alphabetically last, but still in priority list", "Alphabetically first, but third in priority list", -1]
])(
    "'%s' is before '%s' == %i",
    (a, b, expected) => {
        expect(sort(a, b)).toBe(expected);
    },
);