JSFiddle - React, Tailwind, and code Playground

JavaScript

/*
    interface Composite {
        function add(child);
        function remove(child);
        function getChild(index);
    }
    
    interface FormItem {
        function save();
    }
*/

var CompositeForm = function(id, method, action) { // implements Composite, FormItem
    //...
};

// Implement the Composite interface.
CompositeForm.prototype.add = function(child) {
    //...
};
CompositeForm.prototype.remove = function(child) {
    //...
};
CompositeForm.prototype.getChild = function(index) {
    //...
};
// Implement the FormItem interface.
CompositeForm.prototype.save = function() {
    //...
};