how to create container class in css code example

Example: js container class

function Branches() {

    function Branch() {
        var _id;

        _id = Math.round(Math.random()*10);

        this.getId = function() {
            return _id;
        }

    }

    this.createBranch = function() {
        var branch = new Branch;
        _branches.push(branch);
    }

    this.getBranches = function() {
        return _branches;
    }

    this.getBranchIds = function() {
        var branch_list = this.getBranches();

        var branch_ids = [];

        for (var i = 0; i < branch_list.length; i++) {
            var branch_id = branch_list[i].getId();
            branch_ids.push(branch_id);
        }

        return branch_ids;
    }

    var _branches = [];

}

// code test
var test = new Branches;

for (var i = 0; i < 7; i++) {
    test.createBranch();
}

console.log("Branch IDs:\n" + test.getBranchIds());