example.js

function makeTreeView() {
    var officesWithNegs = [];

    var officeCodesWithNegCodes = UserEnvironment.lookups.officeNegotiators;
    var office;

    for (var key in officeCodesWithNegCodes) {
        // Initialise this office
        office = {
            negs: buildOfficeNegotiators()
        };

        // Extra data when possible
        if (officeCodesWithNegCodes.hasOwnProperty(key)) {
            office.code = key;
            office.selected = false;
            office.name = negPickerModal.offices[key];
        }

        // Push onto main array
        officesWithNegs.push(office);
    }

    // This builds an array of negs, the implementation is concealed here as the
    // calling function does not need to know how to do this.
    function buildOfficeNegotiators() {
        var previouslySelectedNeg = false;

        return officeCodesWithNegCodes[key].reduce(formatNeg, []);

        function formatNeg(negArray, neg) {
            var newNeg = {
                code: neg,
                name: negPickerModal.negs[neg],
                officeCode: office.code,
                selected: false
            };

            if (!previouslySelectedNeg && negPickerModal.defaultCodes.indexOf(neg) >= 0) {
                newNeg.selected = true;
                selectedNegs[newNeg.code] = newNeg;

                // limit selected neg to one
                if (negPickerModal.single) {
                    previouslySelectedNeg = newNeg;
                }
            }

            negArray.negs.push(newNeg);
        }
    }

    return officesWithNegs;
}