如何在JavaScript中的构造函数中定义对象的原型？

Question

I'm to creating an object constructor with an object as one of it's properties, and want to add methods to that object's prototype.

Defining it like so doesn't work because the object is instantiated from an object literal and not from a constructor:

 function Resource (options) {
    this.self = this;
    this.options = options || {};

    .. other options. ...

    // service object that I want to add functions to its prototype
    this.service = {
        request: new XMLHttpRequest(),
        requestMethod: options.requestMethod ||'GET',
    },
    // using prototype actually creates an object called prototype 
    // as a property of the service object.
    this.service.prototype = {
        dataToNode: function(element, parent, data){
            var toAppend = document.createElement(element);
            toAppend.innerHTML = data;
            return parent.appendChild(toAppend);
        },
} 

Cutting to the chase and using __proto__ like so works, but __proto__ is depreciated.

How can I add to the objects prototype without using __proto__ ?

function Resource (options) {
    this.self = this;
    this.options = options || {};

    .. other options. ...

    // service object that I want to add functions to its prototype
    this.service = {
        request: new XMLHttpRequest(),
        requestMethod: options.requestMethod ||'GET',
    },
    // using __proto__ works but its deprciated
    this.service.__proto__ = {
        dataToNode: function(element, parent, data){
            var toAppend = document.createElement(element);
            toAppend.innerHTML = data;
            return parent.appendChild(toAppend);
        },
}

Answer 1

function Service(options) {
    this.request = new XMLHttpRequest();
    this.requestMethod = options.requestMethod || 'GET';
}

Service.prototype.dataToNode = function(element, parent, data){
    var toAppend = document.createElement(element);
    toAppend.innerHTML = data;
    return parent.appendChild(toAppend);
};

function Resource (options) {
    this.options = options || {};
    this.service = new Service(this.options);
}